TA Collector

iTrader: (1)

Hey guys, have a question I need opinions on. I've got a '99 SS M6 with AFR 205's, FAST 90, Comp cams 232/234, spec stage 3 clutch, Moser 12 w/ 4.11's. The exhaust is a set of hooker super comps w/ emissions, high flow cats, electric cut out and a flowmaster. My question is that I'm gonna redo the exhaust, but to what extent? Is it worth getting rid of the cats? If it is, what is really my gain to do that (in power numbers and band)? Second, do I need to retune the ECM for the O2 sensors or will putting simulators in be enough? I am completely lost as what to do and am just not sure . I would really appreciate any feed back I can get to make a proper, informed decision on this (oh, it's getting a CME tip and valance if that matters). Thanks everyone.

CorbinLR

iTrader: (10)

probably about 5-15 rwhp and tq.
wont change the power band much if at all
and you could just tune the car to stop it from throwing the bad catalytic converter code. I'm assuming you don't have to pass emissions? If you do, you wont pass without cats.

TA Collector

iTrader: (1)

In beautiful (f-cking cold ) Minnesota. No emissions laws. I'm trying to be conservative with what I spend too. I have room, just don't want this to turn into a problem because I runs so well, don't want to have it go to hell because of something stupid.

MikeWS6

I put some high flow cats on mine to tame it down a bit. Only lost 5hp. The sound quality alone was worth it. If my car was a track only car then I wouldnt bother with cats but I hate that raspy sound that an off road y pipe makes.

intenseblue

iTrader: (1)

You're also stock internal. Makes a larger difference on a head/cam car. ORY and a straight through muffler would probably make a nice SOTP feel.

RevGTO

iTrader: (12)

I'm just bolt-on and went from a 2.5/3" catted Y to a 3/3.5" ORY and picked up .06 first time out with it. Season ended with a .1 gain. There may have been other variables influencing it, but it definitely helped. I was stuck at my previous PB until I made the change.

ULTIMATEORANGESS

iTrader: (4)

if you dont need them go catless. if not get high flow ones.

HWI

iTrader: (2)

Running high flow cats here, helps cut out the rasp, worth it imo.

MikeWS6

Thats true. I cant imagine how loud my lm1/lt setup would be with a strong heads/cam kit and off road pipes

bayer-z28

iTrader: (14)

A sniffer? No it won't pass.... An OBD Check? Yeah it'll pass...

And I never noticed that big of a difference when I deleted my cats.