Less power???
 

I just completed a 1 7/8 Kooks header install on my 2000 Firehawk. The car is completely stock other the a slp lid. I had the car tuned (street tuned so no hp numbers) but now the car feels like it has less power then when it was stock. I have not dynoed the car, but when the car was stock if I jumped on it from 3000rpm up it would start to break the tires loose, now if I pull out and jump on it, it doesn't spin the tires at all and doesn't feel like it pulls the same. Any ideas on what could be the problem?

The headers and catted y-pipe where bought used from a member on here, with about 2000 miles on them.

sounds odd.

i put 1 7/8 hooker super comps on my ta (lid, headers, weld in muffler only). stock tune before the car would spin out of first and a little on 1-2 then stop. now it will spin 1st, and basically all of 2nd. the car will actually spin from a 50 roll in 2nd gear now. it pulls noticeably harder everywhere above 2k rpm.

Either the tune is whack or you're underestimating your butt dyno.

Take it to a track or dyno and see what numbers it puts down. Then we can say if it's the tune or just you.

Was it tuned with a wideband?

Yeah it was tuned with wideband. Is there a chance the cats could be clogged?

And I'll be bringing it to a dyno tomorrow hopefully.

Hey s346K what gears are you using?

what are cats? ;D lol ......with those headers you may lose some low end tq due to the backpressure etc etc.....but power should still come up. take it to be tuned and find out.

the only low end tq loss i noticed was 1-2k rpm. everywhere else the car is more powerful. untuned of course. i'm sure tuning on it would make it even more obvious.

the whole backpressure thing is a myth.

Just had the car on the dyno, 269hp and 276FT/lbs so I guess there's something wrong. My air/fuel went from 14.7 at 2500rpm to 15.5 at 5600rpm. The dyno shop here does not have a tuner so he could not make any changes for me. I'm currently trying to get a hold of the tuner to see what is going on.

That's an awful tune or you have fuel delivery issues. DO NOT, I repeat DO NOT get on your car full throttle again until you fix your fueling issues.

You will quickly melt a piston(s) at that AFR going full throttle.

Yeah tell me about it. I've been using the car for about 2 weeks now and have had it WOT many times, I hope i haven't caused any damage.

My car had the exact same issue! I have everything in my sig and my car only made 270 rwhp off the bat on TSP's dyno, he said I had a fuel delivery problem. We eventually got it tuned up to 340 rwhp but he said it wasn't exactly tuned right either so idk? It's been running fine for about 4 months now. I just don't know where to start in finding the problem. My fuel pressure's where it should be and I have a new fuel filter and all injectors are new. Haven't checked the fuel pump but it seems fine?

id take off the y pipe and drive it open header to see if made a difference. at least you can rule out the cats....

factory 342s..