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Discussion Starter · #1 ·
I just got my car back from the shop where i had the exhaust modified from the turbo back. I added Perrin Cat Back Twin Tip Exhaust. Being new to the modification world, i didn't know how loud each seperate brand of exhaust could be. I was told by the shop where i bought the part and had it mounted that it is on the less noisy side. Its not bad and i am not complaining about the exhaust tune that you hear in the car.

What i was curios to learn is can i add any sound proofing/deadning material to the cabin in order to make it quieter? Has anyone else used any type of product to whether it be spray foam or egg shaped foam pads in the cars panels in order to make the ride inside the cabin quieter?
 

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You can use dynamat... Only problem with soundproofing is the added weight. It's pretty dense stuff and can start to weigh a good amount. You could try and do the floor of the car as I'm not sure how much comes in through the sides. I would guess most of the sound is the resonance from the piping.
 

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Hmm... it sounds like you only had a cat back installed. If you had your exhaust modified from the turbo back, it would include a downpipe AND a cat back - or did you get a downpipe too? If you had an aftermarket downpipe installed, you should also have some type of tune or engine management (Stage 2)...

Almost any aftermarket cat back is going to be louder than your stock cat back. Some of them have silencers that you can install, but they're not very cool. You could install sound deadening material under your carpet and in your door panels, but that will add weight to your car. Or you could get rid of your aftermarket cat back and search around for a quieter one.

If you add a downpipe too, that will make the sound even louder. If you want to reduce cabin noise with an aftermarket downpipe, choose one with a cast bellmouth section (like Cobb's dp). The cast section has significantly thicker walls than a lesser quality dp that simply has a stretched pipe on the end that connects to the turbo. The thick walls of the cast section keep more noise inside the pipe instead of transmitting it inside the cabin.

Honestly, it's a sports car and you installed an aftermarket exhaust... let that baby sing and enjoy the sweet melody ;)
 

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Dynamatting under your carpet is the best way that I know of. It's just the work of pulling all your interior out. I had my last WRX dynamatted, it didn't seem to help a whole lot, but I never had it before the dynamat either.

As for the weight, it's a daily driver right? What's another 15 lbs?
 

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Discussion Starter · #5 ·
I had the exhaust changed from the turbo out to the muffler. The car has an Invidia catted down pipe and Perrin Cat back twin tip exhaust.

I am also running Stage 2 Cobb Accessport after the install.

The car can be loud, i understand that it is a sportscar. But i wanted to mute it just a little bit.
 

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Good call on the resonator. Most I have seen dont run that much, and labor at most shops arent that bad either. And it shouldnt even take that much time either.
 

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Not unless you are trying to really get every last but of HP out of a setup. And if you are still mostly stock, minus like a stage 2 setup you arent going to lose a thing.
 

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Does the resonator reduce performance?
Nope, they are a straight through design. It only changed the frequency of the sound out of the pipe, no back pressure.

Here a good options.

Linky

There are plenty of cheaper $30 options as well.
 

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Here's an answer that's completely out of the box --

I thought our WRX was kinda loud completely stock, and it seemed like much of the noise was coming from the trunk area. I took a couple of Coleman sleeping bags and lined the trunk with them, and it lowered the noise a bunch. It was free (I already had the sleeping bags) and I like the results.

Next thing I did was get the back seat ready for our Golden Retriever. Went down to Wal Mart and bought a king-size comforter (blanket) and put it in teh back seat in a U shape, and then put the "dog tarp" on top of that. Even more quieting! We're pretty happy with the result.

And the best thing is -- if you try it and don't like it, just take it all out again. No harm, no foul.
 
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