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-   -   tuning a must if do downpipe and cat back? (http://www.wrxtuners.com/forums/f51/tuning-must-if-do-downpipe-cat-back-32302/)

tsmithr34 04-07-2012 08:23 PM

tuning a must if do downpipe and cat back?
 
I recently got a 2008 wrx hatch, a shop said I would HAVE to tune the car if I were to put on a downpipe and cat back exhaust. Is it really necessary? I'm just looking to do a couple things to it, not dumping alot into it. Thank you for any replies.

BLAZE2099 04-07-2012 08:42 PM

Not the cat back, but the down pipe... Yes

pzr2874 04-07-2012 08:43 PM

Yes, just for the DP.

tsmithr34 04-07-2012 08:45 PM

because of the cat after the turbo right? thank you

tsmithr34 04-07-2012 08:55 PM

wait, would that matter bacause doesn't the turbo make the back pressure that the engine needs?

newtothegame 04-08-2012 08:55 AM

Search around for pics of the stock exhaust versus any other aftermarket one. The aftermarket ones allow for more are to flow thru them effectively changeing everything in the process. Listen to the people that been doing this awhile, or you can take the chance of ruining your brand new toy.

bad grocerygetter 04-08-2012 10:26 AM

It's because the stock downpipes have a plate over half of the opening. Aftermarket ones do not. Doesn't have anything to do with the cats.

brfatal 04-08-2012 10:44 AM

[quote=tsmithr34;278398]wait, would that matter bacause doesn't the turbo make the back pressure that the engine needs?[/quote]

That's not why you need the tune.

[quote=bad grocerygetter;278429]It's because the stock downpipes have a plate over half of the opening. Aftermarket ones do not. Doesn't have anything to do with the cats.[/quote]

This has absolutely nothing to do with it either. Some aftermarket ones are flat plate as well.

HKS
[IMG]http://www.wrxtuners.com/forums/attachments/f75/4218d1247097995-hks-catless-downpipe-hks_wrxdownpipe.jpg[/IMG]

Greddy
[IMG]http://www.fredbeansparts.com/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/g/c/gcd.jpg[/IMG]




There is a fueling delay between the OL and CL fuel transition. When you remove the cats the turbo spools up faster and the switch happens sooner. The delay needs to be removed so as to prevent a split second where you would otherwise run very lean.

mazzanic 04-08-2012 01:30 PM

Im in the same rut. I have a DP sitting but no tuner. So just make sure u tune or youll blow her up

tsmithr34 04-08-2012 07:05 PM

Thank you very much for clearing that up everyone

Klone 04-09-2012 12:20 AM

or u can get an e-tune. GL

bad grocerygetter 04-09-2012 07:48 AM

Quote: This has absolutely nothing to do with it either. Some aftermarket ones are flat plate as well.

Wow I had no idea! Thanks for sharing that. I knew about the ol-cl delay but I thought it was more with tuning for an intake. But I see how I would be affected with the exhaust stuff.

brfatal 04-09-2012 08:57 AM

[quote=bad grocerygetter;278469]Quote: This has absolutely nothing to do with it either. Some aftermarket ones are flat plate as well.

Wow I had no idea! Thanks for sharing that. I knew about the ol-cl delay but I thought it was more with tuning for an intake. But I see how I would be affected with the exhaust stuff.[/quote]

Bugeyes don't have the delay.

wrxdan 04-09-2012 12:17 PM

i just got a tactrix cable and downloaded ecu flash, then went to xpt tunning and got a stage 2 ots map, works great. probably the cheapest way to get some more power out of it.

u'll be surprised in the difference it makes over stock

Awrecks 04-12-2012 10:15 AM

blew up my 2004 this way ran downpipe with no tune for a year and a half and she blew. do yourself a favor.. get a tune. NOW!


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