Hey guys,

Just curious as to what you guys think is the quietest aftermarket header/dp combo? I have a GMPP catback on my car, and the combo of that and a ZZP header/dp, it was too much. Liked the power, but it was too loud. Any suggestions?

Thanks!

 

I have the GMPP Exhaust manifold, and a 3" ZZP highflow cat downpipe. Is your DP catless? Is your ZZP header a 3 bolt or 2 bolt?

 

My ZZP combo was the 1st gen one. 2.5 tubing. It was the catless originally (used), but I had a cat thrown on. It was still really loud. I'm pretty sure it was the 2 bolt one..

 

get a quieter catback?

 

The catback isn't THAT loud.. lol. It's weird though, because my GMPP catback is louder than any other GMPP that I've revved next to. Even when it's just catback vs. catback. I have no clue why..?

 

you have a sport and they have tuning models maybe?

 

idk what it is about the lsj/echotec but it makes one loud exhaust note. on my last car i had header, no cat one rezi and borla muffler it was super quiet. yet on the cobalt, with stock header and dp, with just a after market muffler it was louder than old car.

now im running pacesetter , cattlest custom dp with a small 6" glasspack, stock pipe with a flowmaster and its unbearable , i feel i like i cant get on it without every cop in the county knowing . i fell bad for people that drive next to me with there windows down. when cursing its not to bad , but any kid of acceleration and its deafening. Im gonna try and replace the stock resi with 24" glasspack and the 6" with a 12" and see if it helps. maybe even switch flowmaster to a supertubo style muffler

 

glasspacks dont really muffle sound too well, and flowmasters sound horrible on an ecotec. Theres 2 problems right there...

 

That's why I took my ZZP combo off. It gave a great increase, but the loudness was crazy. With just the GMPP catback it's loud but deep. With the GMPP and ZZP combo, it was LOUD. lol. Probably sounded sweet doing a drive by, but in the car, it was crazy. I hated getting on it.

Regardless, my GMP Performance was way louder than any that I've been next to. I have no clue why. It shouldn't be THAT much louder because it's a 2.4 compared to a 2.2 as everyone's was. I have no idea..?

 

im in the same boat. Im looking for a quieter replacement exhaust

 

glass packs do enough when not used alone.
which is why they work great in place of resonators or as secondary mufflers. on my last car a 18" glass pack was like night and day. and technly just about all flow threw mufflers are glass packs , there bigger bodys just allow for better sound suppression. and as far as the flowmaster goes , with the stock header/dp it dose sound a bit odd, but with a mid length and 3" down pipe it sounds down right mean. at idle its reminds me old school muscle burble gurgle ,at wot it deep and throaty with no rasp. there is a resonance at 3krpm but it can only be heard inside the car. the small glass pack i added made a pretty big diff, just not enough for me.