phantomzer0

iTrader: (17)

ok, i need to get some new cats, so since the exhaust shop will be cutting a rewelding, i ve decided to go ahead and throw on some headers. heres my question, if i get the headers and put on stock cats, will it hurt my performance, i already know it will impact the sound, but how bad would i loose performance?? also, i have the slp LM on it right now, so since evrything will be 3 inch all the way back, would it be dumb to get the slp CME tip? i read that its only 2.5 so would this also just be stupid to get?? so basically my question, in a nutshell, is how much performance am i loosing if i get cme and stock cats with 3 inch headers and exhaust??

any help and suggestions would be great on what to do.

WILWAXU

iTrader: (6)

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Full-Force

iTrader: (11)

CME isnt gonna change anything. I would go ahead and put hi flow cats on it since you are replacing them. The only headers that stock cats will fit is shorty headers and they are probably not gonna give you much more power than your manifolds. If you are planningon going with longtube headers or mid length headers then the stock cats wont work. If you have to comply with emissions then I guess you have to have cats so I would look into a catted y pipe like the TSP Y pipe and some longtube headers.

TheBlurLS1

iTrader: (8)

Can't use stock cats with LT headers. Check ebay and search magnaflow cats. I have 3" in/out on my 400rwhp f-bod and it does just fine.

The 2.5" rear exit will be fine. Your exhaust system needs the big bad 3" pipe at first because the hot gas is pushing much more CFM than when it cools off at the tips. Another thing to consider is that two 2.5" pipes will definatly flow more than your one, 3" I-pipe, if you go with a y-pipe setup (90% of people).