I've been searching a lot on this and can't seem to find a direct answer. I am supercharged and I have a stock LSJ catback right now. I've read that the stock muffler is the most restrictive part of the catback. I'm debating whether or not it would be better to just switch the muffler to a Dynomax or if I should get a GMPP exhaust.

I know that the stock catback starts at 2.5" and goes down to 2.25" into the muffler. I'm not sure if the GMPP is 2.5" all the way through with a 2.25" outlet or if it is 2.25" all the way through since I've read both.

So what I'm wondering is would it be worth selling the stock exhaust and getting the GMPP or would it be just as beneficial to switch out the muffler on the stock exhaust.

I am not worried about sound at all, I'm more concerned with performance

Thanks for your help.

 

Besides stock catback, what's your setup with header and downpipe?

 

BadMab and ZZP 2.5 catted DP

 

id say go corsa but i had that setup and rasp. but u dont care so

 

I don't have that kind of money lol. I'm primarily looking for GMPP or switching mufflers.

 

I would go with this: ZZPerformance - 2.5 inch Stainless Cobalt Catback Exhaust #ZZ-25CBTCB

But it's your car

 

Gmpp is 2.25 and flows great for your power level. Ppl have had 300hp on m62 with that setup. Lots of aggressive tuning and man pulley but it has been done

 

Ok thanks. So would it be worth spending more money to get the GMPP rather than just switching to a better flowing muffler on the stock exhaust?

 

a 3in downpipe and a muffler swap

the dynomax super turbo is pretty nice, u can get a 2.5 or whatever size and u will need a tip as well

 

Thanks, will that make the flow close to the GMPP exhaust?

 

it will take the restriction of the stock muffler away and flow similar to the gmpp

if u want more flow the super turbo isnt for ya, the super turbo is a chambered design not straight thru like say the Vibrant or even the hahn mufflers on their cat backs

the super turbo will flow and wont be as loud as a straight thru muffler

 

Ok I'm not looking for loud. I'd like to stay away from the ricer sound as much as possible. But what you're saying is the super turbo flows better than stock but not as well as the straight through? I will have some benefit to getting the super turbo and it won't be too loud?

 

Get an LNF muffler. It's straight flow but raspy. Had one on my LAP now I have a Thunderbolt muffler which really quiet down some and still feel the same topend.

 

the super turbo flows fine just not as loud.

my review of the sound thru out the rpm range,

1-3k it sounds deep and nice
3.5 - 5k it can get a bit raspy
5- redline and it oddly quiet hahaha this is WOT

while cruising it is stock like, let off and it snaps crackles and pops my fav ^_^

but i have vibrant hd/dp combo catted and 3in vibrant catback
so the stock catback with diff muffler may sound pretty good....maybe haha

the more opinions the better for ya sir

just my take on the flow and sound benefits

 

Thanks for the input.

This sounds like a good way to go. Unless I can get a straight trade for a GMPP I think this is the way I'm going to go. Thanks a lot.

 

is your car a 2.2 or is it the 2.4?

 

09 Sport 2.2L

 

oh haha i was like why is this in the 2.2 section.

it all makes sense now

 

Yea lol. Do you happen to know if I could use the 2.5" inlet and outlet muffler or if I would have to get the 2.25" inlet and 2.5" outlet muffler?

 

The largest restriction in the stock LSJ catback is the inlet to the resonator (2 1/16" to be exact).

 

Ok thanks. But the muffler is also restrictive right? And switching that out will help flow?

 

It's restrictive up to a point yes....

A straight through designed muffler will work best.

 

So do you think I should reconsider getting the super turbo and get a straight through one? If so, which would you recommend?

 

I don't really have a muffler to recommend, because I run a full catback setup.

I did at one time have a GMPP touring welded onto my stock catback, and it sounded very good, and bumped up throttle response a bit.

 

Ok thanks for all the help. I'll do a bit more research and I'll post what I come up with. I appreciate everyone's responses. From what I've gathered I will go stock exhaust with either super turbo muffler or straight through muffler, or GMPP exhaust if I can find a good deal on one. Thanks again.