A 3" catback isn't really going to net you any major gains on the stock turbo.. The K04 will actually have a more difficult time maintaining boost. Stock catback is 2.75" to the rear axle and the muffler is straight through perforated, so it really doesn't offer all that much restriction.
If a Big/Bigger turbo is in the future, you'd definitely want a bigger catback to utilize it to it's full potential, though.

 

not the best sound quality.

cobalt ss straight piped - YouTube

 

Damn dart, that sounds awesome...thanks for that buddy

thanks chick3n for your response

 

I FOUND EXACTLY WHAT I WAS LOOKING FOR. A 3" STRAIGHT EXHAUST WITH RESONATOR AND CATTED AFTERMARKET DOWN-PIPE...

MPx Exhaust with muffler delete on 09 Cobalt SS Turbo - YouTube

 

this was a shitty run, but you couldn't hear my exhaust at all over this guys honda the other day at the track...haha
j32 accord vs turbo cobalt - YouTube

 

i may just cut my resonator off this weekend and see what it sounds like...

 

Anybody ever end up getting any dyno results for this topic? I kind of want a 3" catback and even if it were a few more horsepower (3-5) I'd be pleased. I certainly wouldn't want to lose any as well. Also, do the 3" exhausts weigh more than our stock catbacks?

 

Yeah, I believe someone proved it wasn't restrictive til 400+whp. You actually need one with the EFR though. I'm sure its restricting you about 10-15hp.

 

Side exit with a magnaflow bullet muffler and big turbo ftw...I love it.

 

mpx exhaust with muffler delete is the best and only gets you 5hp on the stock turbo, but as stated above, on an aftermarket turbo, it is a must have and may give up to 15hp.

 

3inch exhuast is pointless unless you're over 350whp. I have a 3inch catless DP and a 3inch ccat-back with a magnaflow resonator no muffler. Gives it a deeper tone.

 

3" will do nothing if you are on stock downpipe, all your "flow" is restricted by the cats. You'll see 15hp out of a catless dp, but not a 3" over stock dp.

 

If its even 5 whp on stock turbo that'd make me happy... just wish someone had some proof to back it up. Doesn't seem to be a clear cut answer. Nobody ever got dyno'd on this?

 

my tuner told me he dyno his after 3" exhaust was installed and he gained 5-7whp in certain areas with full bolt-ons and catless....$400 is more for sound and piece of mind that you are flowing as much as possible

 

EXACT reason i bought my 3 inch exhaust

 

Hmm. So it isn't so much that it gains you peak power, but it gains you some power across the board then? Also how much does a 3" catback weigh compared to stock? I know the piping is probably a bit heavier because it's larger, but the muffler will be lighter than stock right? I heard the stock muffler is pretty porky.

 

stock muffler weighed like 30lbs..it was pretty heavy for a muffler. i removed it on mine...

 

My turbo xs fl cat back weighs 38 pounds ups says ahah

 

3in catless dp and mpx 3in cat back eith muffler... Sex

 

Anybody have regrets going with an aftermarket catback in terms of sound? I mean the stock exhaust with catless downpipe certainly doesn't sound bad... Just making sure this is what I want hehe. Also, it's not too much louder than stock catback is it (with mufflers on both)? I don't want too much attention.

EDIT: I'm probably gonna be going Mpx.

 

3in downpipe with stick catback is still pretty quiet imo, only time u can actually here it is under alot o throttle

 

the 3 inch mpx makes it silent....i have the res and muffler on it and i love how quiet it is now...its deep and has a noticeable whistle...worth it i think. i started it after i put it on and it was echoing thru the shop i was in...only thing i reccomend is buying 3 bolts the same size....they give u 2 sets...u need 3

idk if the bolts come off the stock exhaust....i banged the snot out of them with a hammer and they werent moving ....luckily the shop hooked me up... Also buy the mounts with the exhaust...the stock ones stretch easy and mine taps against the back axel....i just dealt with it....might fix it when i get back from this deployment

 

So not too much louder than stock but sounds better?

 

yes its not raspy or anything...really clean....check out the mpx website for a sound clip

 

Yeah I did. I find sound clips are never really give quite the full tone though. Gotta hear em in person I find. Never heard anything but good about the mpx one and it's the best priced one for the lnf. Can't argue there