EceSSiveMod

on the ss s/c whats the difference in adding a muffler to the 2.5in exhaust and putting a 2.5in catback on. i know that the stock exhaust shortens right by the rear wheel but besides that why else should i buy a cat back instead of just replaceing the restricted part by the wheel

InfinityzeN

Actually, the stock cat has a nasty restrictive bend and neck down in it. So you won't see as much from a catback with the stock cat still on.

*edit*

I can take pics later, I got my stock downpipe sitting with all the other carparts.

thedubsack85

you really only change exhaust note/tone. and it help's flow alittle cause at the factory resonator outlet the piping goes to 2.25 inches.. so if you go 2.5 it's the same size as the rest of the piping pretty much.

EceSSiveMod

i took out the resonator and just added a muffler...now i have a 2.9 on stage 2 and some local dude said im gona get a lot of knock because my exhaust is to restrictive?!?!

anyone else?

BLAZIN07SS

iTrader: (7)

you will get some knock but nothing outrageous...

EceSSiveMod

someone with a catback would to then rite

BLAZIN07SS

iTrader: (7)

yep, but as i said...its so minimal that its not going to hurt your car

EceSSiveMod

i always wondered y people wasted 600 bux on catbacks

BLAZIN07SS

iTrader: (7)

well its better in the long run if you plan on doing a lot more performance. if you plan on doing just stage 2 and some bolt-ons your exhaust set-up is fine. take my car for instance, i plan on being at about 285-300whp on some spray so i am preparing my car for it. i got a ZZP shorty header with a 3 inch collector, a CTI 3 inch catless downpipe with 2.5 inch bolt-in, and a 2.5 inch megan racing exhaust. i need all this flow because of my future set-up

KillerBee

I bought a complete setup on my car vibrant header and dp and magnaflow cat back i can tell a differnece in my hp

InfinityzeN

^^^

But your talking full exhaust, not just a catback. I noticed a big difference when the tri-y header was added. It only netted me 10whp, but it flattened out my torque curve.

KillerBee

well my cat back made me lose a little low end but gained top end quite a bit but that is because the boost could not get back pressure as good as it did with stock exhaust cause the cat back opened up the air flow

J-RO

can u remove the resanator and it still be legal?

thedubsack85

yes.. removing emission equipment is illegal and you could be put in jail AND fined. resonator is ok to be removed will only make it louder.. a way of getting through the no cat replacement unless it's bad BS is to put the car on jack stand's and take a jack to the cat and put a bend in it.. then it's need's replacing and you wont get fined.. out here in cali there are VERY strict on emission's. like a 100k fine and 6 month's jail time if you replace emission's equipment that is still working fine..

QuikSilverSS

I picked up a bunch of low end tq with my gmpp catback, I was running a stage 2 with 2.8" pulley and a cai, the catback definatly made a difference in the old butt dyno.

ebristol

iTrader: (4)

https://www.cobaltss.net/forums/2-0l-lsj-performance-tech-47/flow-calculation-some-lsj-parts-67539/

I would buy this from CTI and bring it to my local muffler shop and have them weld it up.

https://customtubesinc.com/catalog/p...roducts_id=115

Or if you want to use your own muffler buy this.

https://customtubesinc.com/catalog/p...roducts_id=113

Just make sure that whatever you get is mandrel bent.