You are correct. Just ask Dave D. I have ported manifolds and downtubes with Flowmaster from the resonator back. 1/4 mile dyno says it made more power. The stock resonator and the cats (in that order) are the real restriction with these cars.90coug said:I read here you can port your stock exhaust manifold out and they are just as good as those expensive headers.
You might want to read this.....RBH Racing said:You cut your cats off?
Hope the loss in torque is what you were after. The manifolds on these cars are the real restriction. A good set of headers and high flow cats are the best thing you probably could have done.
I don't think I'll need to worry about them not seeing the cats because they are too lazy to look under the car. They will just fail you and have you do a retest to renew your registration. If that's the case then I can bolt my stock cats back in since it's just clamped together.XR7inWI said:You might want to read this.....
http://www.sccoa.com/articles/cwexhaust.php
Would you actually LOSE any torque by removing the cats... or just shift the torque a bit in the RPM band? I could be wrong there, but even so... these cars have enough torque that if you did actually LOSE a couple lb/ft it would not be the end of the world. The biggest thing is relieving backpressure which will free up some HP. From what I understand about the perceived torque "loss" is that you lose it down low and gain it back (and then some) higher up.
Fact is.. the stock resonator and cats are worthless and that is explained in the article I linked.
As far as passing emissions without cats... It is possible I guess. IF everything else is in top condition and the car is tuned just right. The tune required to pass emissions without cats would likely NOT be the best tune for power and may not even be a safe tune to run without worries of going lean. Someone please correct me if I am way off here, but this is the way I have always understood it. BUT, please give some supporting facts if I am wrong cuz I would like to know what IS right. And by all means, if I am RIGHT, please jump in and say so as well, cuz I am not positive on this. Just going off what I have heard from other sources.
There is one other thing to consider too if thinking about getting emissions testing done without cats. It is possible you could end up with a fine for removing them if you showed up without cats. Maybe you could say the car was like that when ya got it and they would just tell you to get cats installed before it is considered legal. We don't have testing here so I have no 1st hand experience... anyone else?
Tracy
RBH Racing said:oh yeah any real racer knows you would much rather have less tq down low and another hp or 2 up high.
Do What you want with your car man, this forum so far loves to come up with snotty little answers to counter what they don't want to hear. I hope it passes inspection and that it's worth it to you to feel like your car is faster while you rev it harder and faster to achieve the same result.
As for supporting facts do some research on "valve overlap" and the effects of it. Maybe even something called "scavenging" especially on a boosted engine.
One thing that I can believe though is that porting the exhaust manifolds may serve as well as headers on these engines more because of the flow characteristics than the actual rate.
That's assuming it's still on the same cam and head combo it came with.
Jeremy_K said:Why don't you go tell some drag racers with open headers to throw some cats on their exhaust to help them perform a little better.
LOL That's funny! We don't want them harming the environment either. Just think of all that nasty ozone depleting exhaust gas. Oh my word!Blown 91 Bird said:better yet, tell em to put some mufflers on so we dont have to hear that junk
RBH Racing said:oh yeah any real racer knows you would much rather have less tq down low and another hp or 2 up high.
Do What you want with your car man, this forum so far loves to come up with snotty little answers to counter what they don't want to hear. I hope it passes inspection and that it's worth it to you to feel like your car is faster while you rev it harder and faster to achieve the same result.
As for supporting facts do some research on "valve overlap" and the effects of it. Maybe even something called "scavenging" especially on a boosted engine.
One thing that I can believe though is that porting the exhaust manifolds may serve as well as headers on these engines more because of the flow characteristics than the actual rate.
That's assuming it's still on the same cam and head combo it came with.
Jeremy your better off just running some good cats and making improvements else where. It's not worth going through this every year, unless your really going to turn this thing into a 75/25 race/street.
just my .02 like anyone elses.....