Whats your experience on this?

I have a very free flowing 2 1/4 Exhaust. It has flanged straight pipe for the 2nd cat (first cat still in place, 2001) and a custom catback with just a glasspack resonator after the "2nd cat" (now straightpipe) for noise. Then its just a fancy tip at the back coming off the pipe. I cant quite say whether or not my torque has gone down, but I have very good top end though.

Everywhere I look I see catbacks or high flow cats, headers, all these things for reducing restriction. (I know headers create a suction effect on the exhaust too, but even by creating that vacuum effect they are really just making the backpressure 0 or negative psi at a particular RPM). Some people say you need backpressure to run properly. Ok run properly fine, but what about HP and torque?

I mean it misfires a bit on the down rev, but I should get the most HP with nearly a straight pipe to the back right, long as the diameter of the pipe isnt too big as this would decrease exhaust velocity greatly... Am I right?

Does backpressure actually create torque?

-Steve

 

Yes, back pressure creates really nice low end torque. That's why you feel more low end power with the stock exhaust. However, after car's RPM goes out, you don't need any of those back pressure; since your car need least amount of restriction to get air/gas flow out smoothly.

To gain really nice torque, put bored IM and BBTB. In my opinion that is one of the first mod anybody should do (after CAI).

 

Guess you missed my sig... lol :-)

 

LOL. If that's the case, put some nice header there and your car will fly smile.gif

 

Steve, where did you get your TB and IM bored out..?
One of the next things I would like to do..
And what about costs..?

Thx Colin

 

The stock exhaust manifold and stock first cat should provide all the restriction you should need. You should not have any reduction in low end with just removing the second cat and going with a low restriction cat back.

Your car probably FEELS like it has less low end, due to the marked increase in top end, but I would be willing to lay money that if you dyno'd your car before and after, low end would not change.

Installing the 4-2-1 header and a high flow cat back might hurt a tad under 2500 RPM, but my guess is that you would actually see an increase of a ft. lb or two between 2000 and 3500, but again, since the top end would increase SO MUCH, the bottom end would feel weak by comparison.

Butt dyno's are horribly inaccurate. Now you know why.

 

Butt dyno! That's a new vocabulary to me.

 

Thanks Random, I just order a set of 4-1 Headers, this should be interesting...
-Steve