I'm thinking of getting a custom exaust put in, would there be any major (sound, back pressure, etc.) differences between an exit before my rear wheels and the standard behind?

would a dual outlet be a feasible option?

and with the 2.5 engine, how big should the pipes be?

I want to do some engine mods but not in the very near future I don't want to worry about any excess wear and tear on the engine from too little back pressure
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What is your engine set up? I have had a 2003 3.9L and now have a 2004 4.7L, with the V6 you need to keep some back pressure or you loose bottom end power big time you will go from being able to spin your rear tires to not.....with the V8 just the oposite you want to get the hot burnt fuel out of the system asap.
I used Flowmaster's on both and was very pleased with performance and sound.

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DAMN SHE'S HOT!!!

 

I agree

 

ugh. backpressure?

Backpressure is not your goal. Ideally there would be 0 backpressure. What you need is velocity. People get them confused. If your pipes are too big, the gasses slow down and you loose the scavenging effect of a properly tuned exhaust that actually pulls more spent mixture out of the engine. Spent (inert) gasses in the chamber = loss of power.

So to keep exhaust velocity up, you need to keep the volume of the pipe down. A side effect is backpressure, but that's not the goal. Again in an ideal situation there would be high velocity with no backpressure, because backpressure by definition is restricting the flow of gasses out of the motor, which is exactly the opposite of what you want.

On the flipside, if your pipes are too small, you can't flow enough volume of exhaust gasses to keep up with the air that the engine can pump through at high RPM, causing it to choke. To really figure it out, you should calculate the max cfm of your engine at max rpm and then figure out if that'll cause a loss of low end power, then adjust to the best compromise between lost torque and lost horsepower.

While the v8 has more torque you'll still lose some if you don't properly size your exhaust pipe, just like with the 3.9 or any other engine. You may not notice the difference as much, due to the fact that it's got a lot more power in general, but the loss will be there.


A 2.5 liter should run probably 2.25" pipe (single), 2.5" maximum, unless you're using forced induction. a dual tip would be fine if it's a Y right at the end, but pointless. Dual pipes would look funny, as you'd have to figure out what size to use, I'm guessing that dual 1.75" pipes would be about right, but would look stupid.

 

I'll agree, small pipes look bad.
I'll probably have him just cut it short and hide the outlet

I have question about the velocity you're talking about.
what if one were to use one of those tornado intake spinner things in the exaust right before the cat?
I did a test and they do increase air velocity, but are innefective in the intake. but would they do anything in the other end because there is little to obstruct the flow?

just something to think about
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Yes back pressure, you are right the goal is lowering back pressure but I just wanted to state the fact you do loose low end in doing so in a 4 or 6 cyl engine........but I do agree duals on a 2.5L is a waste it will sound like a giant Honda (Lawn Mower) HEHE

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It already does. I've got holes all over the place
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Hole-y Exhaust Batman!

*sorry, I had to.*

 

just like I HAVE to smack you?

J/K
* evades into the night

I will probably just have him put a short downpipe after the muffler bolted directly to the cat
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