Age old debate.. 2.5" vs 3" exhaust...

[mach1033]

I do already have a qa1 kemember, so fitment shouldnt be an issue. Also, I will not be buying the parts quite as expensive as you. Posi's group buy on kooks gets me headers shipped to me for $990, and i am buying the 3" flowmaster kit for the 86-93 lx which includes an x pipe for $570. Add a couple hundred for better mufflers and That is still less than $2k, not including the money I get in return for selling my current setup.. All labor will be done by me, so no money spent there. And I agree about the pulley on my 2.3, thus it is my race only setup. My street setup is the 3.5"/4lb that makes 16psi. I am hoping on the race tune to see at least a 20hp increase.

Is there a thread with Posi's group buy for the headers? I'm interested in it.

 

[timspony]

I have a 3" CB on both of my.Cobra's...and I'd never look back!
Plus 3" has a totally different sound

 

[Lstruck03]

Is there a thread with Posi's group buy for the headers? I'm interested in it.

he started a thread in the 03/04 section on modular fords.

 

[zeusha]

With the power and setup your engine is at 3" exhaust would be more beneficial

 

[black 10th vert]

I do already have a qa1 kemember, so fitment shouldnt be an issue. Also, I will not be buying the parts quite as expensive as you. Posi's group buy on kooks gets me headers shipped to me for $990, and i am buying the 3" flowmaster kit for the 86-93 lx which includes an x pipe for $570. Add a couple hundred for better mufflers and That is still less than $2k, not including the money I get in return for selling my current setup.. All labor will be done by me, so no money spent there. And I agree about the pulley on my 2.3, thus it is my race only setup. My street setup is the 3.5"/4lb that makes 16psi. I am hoping on the race tune to see at least a 20hp increase.

I'm not saying that going with 3" won't benefit your setup, but inmo 2k to gain 20hp is ludicrous! For that same 2k in addition to what you could sell the 2.3 for, you could have a 3.4, and I guarantee that would make a hell of a lot more than 20hp! Like I said, not trying to discourage you, but there are way better bang for the buck mods than slightly bigger exhaust for that kind of money.

 

[GodStang]

I do already have a qa1 kemember, so fitment shouldnt be an issue. Also, I will not be buying the parts quite as expensive as you. Posi's group buy on kooks gets me headers shipped to me for $990, and i am buying the 3" flowmaster kit for the 86-93 lx which includes an x pipe for $570. Add a couple hundred for better mufflers and That is still less than $2k, not including the money I get in return for selling my current setup.. All labor will be done by me, so no money spent there. And I agree about the pulley on my 2.3, thus it is my race only setup. My street setup is the 3.5"/4lb that makes 16psi. I am hoping on the race tune to see at least a 20hp increase.

The kmember is what cost me so much. I got the kooks 1-7/8" a few months ago for $900 new and a full 3" stainless steel catback for $400. The rest was to make it fit on my car. Please do not put flowmasters on a modular car. They flow horrible and sound even worse on mod motor. I love them on a fox body though.

 

[Lstruck03]

The kmember is what cost me so much. I got the kooks 1-7/8" a few months ago for $900 new and a full 3" stainless steel catback for $400. The rest was to make it fit on my car. Please do not put flowmasters on a modular car. They flow horrible and sound even worse on mod motor. I love them on a fox body though.

I disagree on the sound, but I do agree with the flow, that is why I mentioned that I would be buying the kit, but replacing the mufflers with magnaflow. I see no point in going to a bigger diameter exhaust but with more restrictive mufflers.

$400 is a hell of a price for a 3" ss catback. Unfortunatly they are much harder to find for a sra car. Bassani makes one but include the x pipe and is $800.

 

[Lstruck03]

I'm not saying that going with 3" won't benefit your setup, but inmo 2k to gain 20hp is ludicrous! For that same 2k in addition to what you could sell the 2.3 for, you could have a 3.4, and I guarantee that would make a hell of a lot more than 20hp! Like I said, not trying to discourage you, but there are way better bang for the buck mods than slightly bigger exhaust for that kind of money.

i think you missed the part where I mentioned that I could sell my current setup and recoop alot of the cost. Out of pocket would be at or less than $1000 said and done.

 

[Crackerballer]

I'd do ARH 1 7/8 primes to a 3" collector, have Nick make you a 3" x pipe, and buy the 3" SRA bassani and have Nick send you a 3" end to cut off the bassani 2.5" reducer and you'd have a true 3" system.

I had a post in the exhaust section a while ago about this...

EDIT: Found it
http://www.svtperformance.com/forums/exhaust-215/750458-whos-running-full-3-irs-midpipe-back.html

 

[SlowSVT]

Ford equipped the car with a 2 1/4" system with some awful kinks in the mid-pipe (cat back wasn't so bad). Despite that it's a fairly large exhaust compared to most cars. A nice mandrel bent 2 1/2" low restriction system will allow the exhaust to breath while maintaining exhaust velocity to help scavenge the cylinders. When you increase the pipe diameter to 3" you will start to slow the exhaust velocity which may actually hurt the performance of the exhaust system. The larger pipe will also increase the exhaust resonance leading to the dreaded "drone" :uh oh:

If you're running big boost, stage 3 cams, ported heads, high rpm valve gear and planning on keeping the tach needle north of 6 grand most of the time I say a 3" system makes sense. That my friend is a BIG pipe and there are two of them! For a high end Terminator that mainly lives on the street a 2 1/2" system should make the engine a bit more responsive with a sharper exhaust tone and more ground clearance. What little you will lose on the top end with a 2 1/2" system you will make up for it everywhere else. The vast majority of Terminator exhausts sold are 2 1/2" and there is a reason for that.

I don't think it's worth spending the money replacing what you already have.