LOL @ Ryan.

Damn Alan you sure do spend a lot of time trying to get the point over dont you, I normally just give my $.02 and if people dont agree oh well Everyone knows my take on it, go 3" and be done with it. Your only going to regret not doing it down the road when you put heads/cam on, or n2o, or a blower, etc... and everyone knows theyll eventually do a major mod

 

Ken, look through the thread again.

A brief recap:

1st response, my 2 cents

2nd and 3rd, answers to questions which were directed at me

4th, trying to lend some perspective to the question of low-end torque. Did it help any? Did anyone maybe look at the question a bit different afterwards? Maybe.... and that's the whole point.

5th, misinformation and confusion because the person is rambling off things they read and obviously didn't comprehend. Just leads to more confusion and I believe post like that should be discredited in any way they can. Just like a any good lawyer would do.

Since my last response, I've been to this forum maybe three times without a response to this thread. I've spent 10-12 cents so far so I'm still good for a debate. Just pacing myself.

Besides, what do you learn with responses like, "I use 2.5" cause 3" looks too big so you use that too"........ "Well, I disagree use 3" cause 2.5" looks too small and I think thats the best". Boring.

-Mindgame

 

My midpipe is a single 3" pipe. It does split again over the axle into 2-2.5" pipes leading to a small magnaflow muffler on each side of the car. I was going to go with 2-2.5" but changed my mind. The single 3" has done an adequate job. I would probably gain a few horses with a dual setup but with the converters on the car, what's the point anyway.

 

I meant what i said in a good way Alan. Its nice too see you keep debating and giving good info.

 

Yeah, personally I like all the debate going on. It is very intersting to me. I could seriously read this go on forever. Almost like whowever presents the better case is the one I am going to choose, a lot like the lawyer comparison just made

-Chris

 

im still very curios myself. whatever i run has to go over the axle cause i have a gfx kit with cut outs in the back but i dont know about cutting my panhard bar? that doesnt sound to good to me. plus i do drive the car a good bit on the road. but i am gonna be building a 396 so maybe i need the 3" hell im confused

 

Well, with that 396 I would definately go with the dual 3", but over the axle could be a problem. You dont actually cut your panhard bar. There is another bar above your panhard bar that is just there to brace the bracket that the panhard bar connects to. If you could modify it so that it is does not come down as low, and maybe strengthen it if you are worried you may be able to do it. If you absolutely have to have it come out the back your only other real choices are to go under the axle which can work and not hurt ground clearance to much if done right, or run the 2.5". I dont really like the under the axle setup, but I have seen it done to where it didnt look that bad and had pretty good clearance.

Ben

 

396.... definitely 3".

-Mindgame

 

Do NOT run the piping under the rear axle. When you jack the car up the rear suspension will drop and the axle will bend the heck outta your exhaust

Go with some 3 inch piping, I did and have no regrets. This scavenging bs people keep talking about only applies to the exhaust manifold... you use long tube, equal length headers because they generate the correct scavenging properties. They end in a 3 inch collector, if a 2.5 inch collector was the right size then that's how they would have been made.. but no, they went with 3 inch for a reason.. sticking a 2.5 in exhaust on there is not going to net you any gain over 3 in that's for sure.. if anything it will rob you some hp and tq under certain circumstances. My 3 inch setup does have some clearance problems but they aren't that bad.. just drive slowly over speed bumps. I'm convinced that when/if I do it over again I'll use oval 3 in piping and have no clearance issues.

My .02

 

what about a 2.5 inch with an x pipe and then 3 inchafter the x and have bullet mufflers. Read something like that in the article posted erlier, larger piping after the x to decrease backpressure for teh upcoming mufflers and the 2.5 inch to keep the velocity higher before teh x. Would going from a 3 inch collector to a 2.5" pipe hurt power?

 

I forgot to mention in my earlier post that I did lose some low end torque below 3000 rpm as evidenced by my dyno graph. I also felt a loss of torque in the low end, and a great gain in torque in the upper rpms by the seat of the pants. Whether I can tune out that low end torque loss I don't know, it is probably the camshaft.
A single 3.0" straight exhaust pipe will carry over 1000 cfm of exhaust flow. You have to ask yourself if your engine is capable of exhausting that much flow. What happens is the velocity of the flow will increase as the pipe diameter decreases. The velocity will max out at a certain point to where backpressure will begin.
A dual 3.0" will do you no good if you have restrictive mufflers and or cat converters also. I know my magnalfow mufflers are capable of around 600 cfm flow each. Very few flowmasters will flow this much, but they sound good.