Perrin cat-back exhaust (street tuned) - Page 2 - Subaru WRX Forum
Reply
 
LinkBack Thread Tools Display Modes
post #16 of 45 Old 11-30-2009, 08:40 AM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
Ok well Friday morning was a success! I got my Perrin Catback, Kartboy Bushings, and my Subaru 75W-90 Extra S tranny fluid all done! The tranny fluid change went quickly. The exhaust then was pretty easy. The bolts weren't rusty and came off without a hitch, I used the stock doughnut gasket and it seems to be working just fine! And other than it being a little tight when trying to get the bushings in, those went in just like others had instructed. So overall I'm happy with everything that was done. The exhaust has a nice deep rumble now. It's only noticeable when I really gas it, but If I'm just cruising whether it be on the street or highway, you really don't hear it at all, and that's exactly what I wanted! So now i'll be on the lookout for a nice catted DP, preferrably Cobb, but we'll see what comes along...
But another question...So when i do get a DP, would I want to get a larger doughnut gasket, or use the new flat gasket I got that the guy gave me?
airplnmdls is offline  
Sponsored Links
Advertisement
 
post #17 of 45 Old 11-30-2009, 11:26 AM
WRXtuners Member
 
Join Date: Sep 2009
Location: Michigan
Posts: 2,158
RcrsWetDream is known to be trustworthy and helpful RcrsWetDream is known to be trustworthy and helpful
Depends on the brand... Cobb you'll need a bigger donut. Perrin usually has a flat flange so you'll have to use the adapter and a reg. 3" exhaust gasket. You could also use the adapter on the Cobb if you want though, but you'll still probably need the gasket so it might just be easier to get the donut and call it good.

-Chris
RcrsWetDream is offline  
post #18 of 45 Old 11-30-2009, 12:19 PM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
gotcha...thanks!
airplnmdls is offline  
post #19 of 45 Old 12-01-2009, 02:00 AM
WRXtuners Member
 
man show's Avatar
 
Join Date: Apr 2007
Location: Maryland
Posts: 3,172
Images: 2
man show is a WRX expert worth listening to man show is a WRX expert worth listening to man show is a WRX expert worth listening to
Actually, you don't need any adapter if you get a Cobb downpipe - that one's made to use either a factory donut-style gasket or a flat 3" 2 bolt gasket. I would know - that's the one I have. Right now, I'm using a flat 3" 2 bolt gasket to connect my Cobb catted dp to my HKS Hi-Power Carbon Ti cat back. No exhaust leaks, perfect fitment.

Also, you might want to keep an eye on that donut gasket. For a short period of time, I had my stock dp -> factory donut gasket -> 3" cat back w/ a flat flange and the donut gasket sustained some minor damage in the form of circular cuts/grooves from the inner edge of the cat back contacting/vibrating against the gasket. It's not really made for that type of connection, so I'd assume over a long period of time, you might develop a leak - especially if you're using the factory spring bolts since they allow for some movement at that connection point.

John
07 WRX
man show is offline  
post #20 of 45 Old 12-01-2009, 08:30 AM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
O wow ok I'll keep that in mind thanks... How long is a "short time"? By that I mean how long did you have your stock DP and aftermarket CBE on for?
I'd like to buy a downpipe soon and I would if I could find it for cheaper than $600...just waiting for a deal though...
It'd be ok to use the stock spring bolts to connect the DP to the CBE when I do get it, correct?
airplnmdls is offline  
post #21 of 45 Old 12-01-2009, 09:34 AM
WRXtuners Member
 
Join Date: Nov 2009
Location: Ohio
Posts: 13
09wrxboy is an unknown
i have a Perrin 3" catback exhaust on my 09 wrx and i love the way it sounds. It's easy to install and looks awesome. There is a video clip on youtube of my car doing a flyby on the strip out in Canton, Ohio. There is a little highway background noise, but you can hear it after the car goes by the camera really well. Just go to youtube and type in "2009 Wrx 5MT 3" exhaust". The clip should be under 30 seconds. If I was not at work right now, I would find it and paste the link in, but I do not have access to youtube at work lol. Lmk what you think.
09wrxboy is offline  
post #22 of 45 Old 12-01-2009, 10:58 AM
WRXtuners Member
 
man show's Avatar
 
Join Date: Apr 2007
Location: Maryland
Posts: 3,172
Images: 2
man show is a WRX expert worth listening to man show is a WRX expert worth listening to man show is a WRX expert worth listening to
Quote:
Originally Posted by airplnmdls View Post
how long did you have your stock DP and aftermarket CBE on for?
I'd like to buy a downpipe soon and I would if I could find it for cheaper than $600...just waiting for a deal though...
It'd be ok to use the stock spring bolts to connect the DP to the CBE when I do get it, correct?
8 days (I keep good records)

I bet you'll be able to find a decent deal with all the holiday specials coming up - maybe only 10-20% off or free shipping, but it's better than full price. Don't forget, you'll also need a heat shield, unless you want to cut up your stock one

I used two regular nuts and bolts when I finally put my Cobb dp together with my HKS cat back using a flat 3" 2 bolt gasket, but I have a short flex section in my cat back which basically does the same job as the spring bolts. I'd say if you're not using a donut gasket and you have a flex section somewhere between your turbo and exhaust tip, regular bolts are probably what you want. I think my main issue was also that the flanges were too thick and the spring bolts simply were not long enough to hold things together. I might have only gotten the nut on one or two threads and the springs were almost fully compressed when I tried, if I remember...

John
07 WRX
man show is offline  
post #23 of 45 Old 12-01-2009, 11:54 AM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
Man show: Hmm... yeah my CB does have a little flex section, so I'll keep that in mind if the stock bolts won't work... And o yeah thanks for reminding me about the heat shield, just wondering though, is one REQUIRED, or just a good idea? Should I be worried about using that stock doughnut gasket for a few months?

RcrsWD: How long have you had your setup on there for? you notice any problem like man show is talking about?

09WRXBoy: Yeah I can't go on youtube at work either I'll try to check it out later tonight!
airplnmdls is offline  
post #24 of 45 Old 12-01-2009, 12:21 PM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
^^^Look at post #23 too^^^

Also, do you guys know of any issues or know of which gaskets I would need to use with a Perrin or Helix Catted DP? I know bellmouth is better than divorced,but is it just a little worse, or a big difference?

Last edited by airplnmdls; 12-01-2009 at 01:28 PM.
airplnmdls is offline  
post #25 of 45 Old 12-01-2009, 02:14 PM
WRXtuners Member
 
turmic's Avatar
 
Join Date: Jul 2007
Location: Pennsylvania
Posts: 4,371
Images: 6
turmic is a WRX expert worth listening to turmic is a WRX expert worth listening to turmic is a WRX expert worth listening to turmic is a WRX expert worth listening to
Send a message via AIM to turmic
Divorced normally is suppost to be better due to the seperating of the IWG gases and the exhaust gases. But, normally its not a fool proof thing. The divorced section doesn't totally divorce, can cause clearance issues and hit your turbo, or it could keep your wastegate from fully opening through clearance issues. It can just be a hassle at times. Boost Addict ended up shaving down his divorced section because it was having clearance issues.

Kirt
378awhp/373wtq Custom Dom 3 & CBRD tuned 2006 STI.
"When in doubt...flat out" - Colin McRae
turmic is offline  
post #26 of 45 Old 12-01-2009, 02:24 PM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
Gotcha.... This one website I was looking at says that the bellmouth is for bigger turbos (which I doubt mine is correct?) and even though it could be used, I got hte impression that divorced is good enough...it also says that yeah the part sticking out of the divorced might have clearance issues with aftermarket turbos, well what about stock? Should that fit fine?

After looking around a little I've decided to look into probably either the Cobb or Invidia catted Dp for sure...I think since I want it sooner than later lol I might be on the look out for the Invidia. The cheapest I can find it new is here Invidia Subaru Impreza WRX & STi Catted Downpipe for $460. I might see if I can get a new or used one on ebay for cheaper. The Invidia ends with a 3" diameter correct? So I should use a flat 3" gasket to connect it to the Perrin CB, correct? Thanks everyone for all the responses, they are very helpful!

**EDIT**: Yeah after looking around on ebay for a catted Invidia DP it seems a few people are selling them for $450 shipped...That might be something to consider...
airplnmdls is offline  
post #27 of 45 Old 12-01-2009, 06:45 PM
WRXtuners Member
 
man show's Avatar
 
Join Date: Apr 2007
Location: Maryland
Posts: 3,172
Images: 2
man show is a WRX expert worth listening to man show is a WRX expert worth listening to man show is a WRX expert worth listening to
Yep, a flat 3" 2 bolt gasket should be just fine and an Invidia catted dp is a pretty good choice.

And about the turbo heat shield, it's not absolutely necessary, but it's a pretty good idea to have one. Just look at where your intercooler is in relation to the turbo and think about how hot your turbo gets. Fact: hot air rises. Without a piece of metal blocking some of that heat, your intercooler will absorb a pretty good amount and won't be able to cool the charged air as efficiently as it could and you'll end up losing a little bit of potential power because cooler air entering your engine makes more power than warmer air. I realize that some of the air that enters your hood scoop is divered over the turbo and that takes care of some of the heat, but when you're idling in traffic or just moving very slowly, a heat shield will definitely help out with heatsoak issues.

Another effect that a turbo heat shield has is keeping more heat close to and inside the turbo. Fact: hotter air moves faster than colder air. The whole point of a turbo is to use the exhaust gases to spin a turbine and suck in and compress fresh air and send it to your engine. Technically, it would be best to only keep heat inside the "hot" part of your turbo, but a heat shield is an easy way to keep heat next to and ultimately inside the entire turbo. Don't worry though, your intercooler will cool the fresh air a little before it gets to the engine. Anyway, those are the two main reasons for having a turbo heatshield.

A third reason (not really a good one) is simply to add a little under-hood bling with a shiny Cobb (I don't think these are being made any more) or SPT unit.

Coating the turbo itself and/or adding a turbo blanket is the best option, but they can be sort of ugly and/or expensive. A heat shield is an inexpensive option that works better than nothing.

I think it's pretty amazing how everything works together.

John
07 WRX
man show is offline  
post #28 of 45 Old 12-01-2009, 08:11 PM
Moderator
 
newtothegame's Avatar
 
Join Date: Dec 2006
Location: Maryland
Posts: 6,493
Images: 4
newtothegame is known to be trustworthy and helpful newtothegame is known to be trustworthy and helpful
Send a message via Yahoo to newtothegame
Quote:
Originally Posted by airplnmdls View Post
Man show: Hmm... yeah my CB does have a little flex section, so I'll keep that in mind if the stock bolts won't work... And o yeah thanks for reminding me about the heat shield, just wondering though, is one REQUIRED, or just a good idea? Should I be worried about using that stock doughnut gasket for a few months?

RcrsWD: How long have you had your setup on there for? you notice any problem like man show is talking about?

09WRXBoy: Yeah I can't go on youtube at work either I'll try to check it out later tonight!
Quote:
Originally Posted by man show View Post
Yep, a flat 3" 2 bolt gasket should be just fine and an Invidia catted dp is a pretty good choice.

And about the turbo heat shield, it's not absolutely necessary, but it's a pretty good idea to have one. Just look at where your intercooler is in relation to the turbo and think about how hot your turbo gets. Fact: hot air rises. Without a piece of metal blocking some of that heat, your intercooler will absorb a pretty good amount and won't be able to cool the charged air as efficiently as it could and you'll end up losing a little bit of potential power because cooler air entering your engine makes more power than warmer air. I realize that some of the air that enters your hood scoop is divered over the turbo and that takes care of some of the heat, but when you're idling in traffic or just moving very slowly, a heat shield will definitely help out with heatsoak issues.

Another effect that a turbo heat shield has is keeping more heat close to and inside the turbo. Fact: hotter air moves faster than colder air. The whole point of a turbo is to use the exhaust gases to spin a turbine and suck in and compress fresh air and send it to your engine. Technically, it would be best to only keep heat inside the "hot" part of your turbo, but a heat shield is an easy way to keep heat next to and ultimately inside the entire turbo. Don't worry though, your intercooler will cool the fresh air a little before it gets to the engine. Anyway, those are the two main reasons for having a turbo heatshield.

A third reason (not really a good one) is simply to add a little under-hood bling with a shiny Cobb (I don't think these are being made any more) or SPT unit.

Coating the turbo itself and/or adding a turbo blanket is the best option, but they can be sort of ugly and/or expensive. A heat shield is an inexpensive option that works better than nothing.

I think it's pretty amazing how everything works together.
I hate to go against you John on this one, especially since you mentioned Cobb. But I have the stock heatshield on my 07 that has a 20G on it, and my 05 that has a TBE on it. If money is tight, just trim up the factory heatshield so it fits over the DP and you will be fine. But if money isnt an issue do as mentioned above and get you a nice Cobb piece. Even though its known to loosen up sometimes and rattle (Idk if you have had this problem John) it does look nice.

Joshua
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX
Cobbtuning.com"
newtothegame is offline  
post #29 of 45 Old 12-02-2009, 12:38 AM
WRXtuners Member
 
man show's Avatar
 
Join Date: Apr 2007
Location: Maryland
Posts: 3,172
Images: 2
man show is a WRX expert worth listening to man show is a WRX expert worth listening to man show is a WRX expert worth listening to
Oh yeah, no problem.. I forgot to mention that.

I was actually just thinking about trying to compare the two side by side. As far as thickness, the Cobb shield seems to be made of slightly thicker metal than the stock piece. However, the general shape/design of the stock shield - even if you trim it enough to fit around a bigger aftermarket dp - seems like it would hold in a little more heat than Cobb's unit. I don't know... I guess when it comes down to it, any heat shield is better than no heat shield.

And nope, my Cobb heat shield hasn't come loose in the 31,000+ miles I've had it on - although I did have that issue a while back where the wastegate actuator arm was occasionally rubbing against the edge of it, but I trimmed it and now everything seems ok. I'll definitely keep an eye on it and if I start to hear anything rattling and I'll be sure to post and let everyone know. A dab of threadlocker on the bolts might fix that problem - unless the extreme heat renders it useless...

John
07 WRX
man show is offline  
post #30 of 45 Old 12-02-2009, 08:12 AM Thread Starter
WRXtuners Member
 
airplnmdls's Avatar
 
Join Date: Jun 2009
Location: Ohio
Posts: 212
Images: 10
airplnmdls is an unknown
Send a message via AIM to airplnmdls
Thanks guys! The only thing I'm worried about now still is what manshow said about the rubbing...you think that's something I should be really concerneced about? Also how much of the stock heat shield would need to be shaved off?

Last edited by airplnmdls; 12-02-2009 at 10:40 AM.
airplnmdls is offline  
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On