CGLHawk260

Off road pipes 431 hp 404 tq. With cats 410 hp tq 389. I put the cats back on 2 years ago to pass emmissions. I had a check engine light so i had it re tuned . I new i was down on power because of the cats. The only thing i didn't like about the off road pipes is that after driving the car for a 1/2 hour I turned green and had watery eyes. Cats kill the smell but kill your hp numbers.

Oh well maybe i'll go back in June.

DannoWS6

iTrader: (5)

Wow that's a big gain, 20hp. I can't wait to see what my car puts down. The #'s in my sig are w/ cats too. I know taking them out at the track gave me another .15+ and a mph.

I agree though the smell sux and after you go for a ride that's what you smell like all day.

2MCHPWR

iTrader: (10)

so you are saying two years ago, with cats it made 410hp?
but now with a new tune it makes 431 with cats removed?
what brand cats? did they look clogged or collapsed?

JL ws-6

iTrader: (50)

I wonder what my car would do without the cats and just open headers...

Might have to find out this summer before the pinks allout shoot @ MIR, maybe the exhaust will find itself taking a vacation for that weekend

CGLHawk260

Sorry.
NO, I lost 20 hp by adding the CATs. 2 Years ago with NO Cats I had 431 Hp and 401 TQ ..I wish i gained!

iamsickofitall

iTrader: (18)

damn, those must have been some really low flowing cats. what brand cats? did they look clogged or collapsed? most results are more in line with what DannoWS6 saw

1slowls1

iTrader: (1)

My car dynoed with cats 427hp and 385tq ive got the magnaflow cats.

CGLHawk260

The cats that came with the SLP headers. I can't remember.

1slowls1

iTrader: (1)

No came on the QTP y-pipe

thechef

iTrader: (13)

I remember when i took my SLP cats off i gained 15 hp and 15tq in the curve

ShevrolayZ28

iTrader: (4)

Nice. I remember after pricing a FAST 90/90 and considering the gains, I went out to the garage and gutted my cats instead.

Some day I'll get the FAST....

lilstephsls1

iTrader: (5)

Neat, that makes me think what my car would make without cats.

ULTIMATEORANGESS

iTrader: (4)

wow, and i always thought good high flowing cats didnt rob alot of power. at least with motors making 500rwhp or less.

Slowhawk

iTrader: (12)

SLP Cats are horrible.I wonder what you would make if you ditched the SLP header and go with Kooks or QTP.We've seen 10-20rwhp gains.
Kook header Cats work very well.Ussually 5hp or so difference on a H/C car.

JL8Jeff

iTrader: (14)

You can't compare a car tuned without cats to just putting the cats back on without re-tuning. If you re-tuned with the cats I bet the hp loss would be closer to 5-10 hp at the most. It's like dynoing stock manifolds to headers without tuning. Why bother even dyno it.

Slowhawk

iTrader: (12)

I've done it.Some cats lose alot more than others tuned 100% back to back.Most good cats only lose 5-10rwhp.
An acception was Brent's Vette which gaine 60rwhp getting rid of the Cats.But this was a 427 FI setup.

02SCVette

iTrader: (3)

That's why I went with the Kooks 3" catted set up. No nasty stench and minimal power loss. Nice compromise I think.

gd1996

iTrader: (9)

I dunno about hp, but my ta passed with a hollow cat, no tune. So cant see why a hollowed or something that appears to be a cat couldnt be added and left at that and no mess with swapping then,

ynkssws6

iTrader: (1)

Holy crap that's a big diff! That car is sick though

pdd

iTrader: (3)

random high flow cats make about 5hp(or less) compare to straight pipes(proven on the corvette forum). ill take that loss over the smell any day