If you have a high horsepower C4 what are you running for an exhaust system. (High Horsepower = 400RWHP Mustang dyno neighborhood.)

I have EM LTs high flow cats and a factory catback and some experts that I trust believe my exhaust is costing me power. Corsa looks to be a step down, B&B looks interesting, however, is there something better?

g,day mate.
r.e your exhaust upgrade,im not sure about brands as you have mentioned but i am building up a high horsepower engine in the 450 plus hp range and i have 1/3/4" diam long headers, then high flow cats, then i am running a x-pipe into true dual 2.5 " inner diameter mandrel bent pipes all the way back thru to magnaflow rear high flow mufflers which i beleive should be suffucient!
if you go to large inner diameter pipes, you can loose important back preasure.
may be 2.75 " each pipe would be max i would go.
i think the important parts are x-pipe,true dual exhausts helps alot.
hope that sheds some lite for ya!
cheers
glen

I've not dyno'd yet but expect in the range of 400+ rwhp.

Stainless SLP shorties.
Bullit cats.
X pipe.
2.5" pipe.
Dynomax mufflers.

The shorties suffice for now but had the bullit cats and X pipe set back far enough to allow for future long tubes. The X pipe sweetens the sound nicely (especially @ high rpm's). The Dynomax mufflers got rid of 95% of my resonance.

It works well together plus was quite inexpensive compared to a package system.

What makes you think you're leaving something on the table? What exactly are they saying is wrong with it?

I have a very novel idea for you Mike, its something ive always considered alot smarter than blowing thousands on a brand name exhaust, and that is bend up your own.

Its cheaper, its going to be better, its custom exactly what you want for the car, and youre not wasting a truck load of money on brand names that dont mean a thing when it comes to making power.

The only brand name pieces in my exhaust are the GENIE stainless mufflers, and they were only $90 AUD a piece, stainless pipe is not anywhere near as expensive as brand name exhaust manufacturers seem to make it out to be.

Case,

That is probably the route I'm going to take. I was just wondering if someone had dyno/track proven high flow exhausts.




JSUP


as for the question on why I thought I was leaving something on the table is I have the same package as some F-body guys and there's a delta between my results and theirs, since one of the major differences is that I have cats and full exhaust vice open exhaust. I was asked on how well my exhaust and headers were.




Another difference is IRS vice solid rear.
I believe the IRS will dyno lower due to rotating mass and driveline losses; but IRS vice standard diff probably does not add up to the delta. However, 15-30 hp from exhaust would go a long way towards finding the missing power.


Mike

Mike, I got to thinking since our recent emails. I've got some nice stainless 2.5" stuff that you could easily make a custom true-dual system out of. I've got some Corsa pipes that go from the headers to the resonator/X-pipe and also some pipes that branch off to the mufflers from the differential area. I probably also have enough straight stainless too, to fill in the gaps from the resonator (or X-pipe) back to the axle where it branches off to the mufflers. Everything that needs to be bent already is, and it's mandrel too. I also have a stainless C4 X-pipe but it's 3". I'm not sure yet if I want to get rid of it anyway. But most of other stuff is just lying around except for the rear pipes to the mufflers. And they'll soon be off of the car. Let me know what you decide and maybe we can build you a sweet system for on da' cheap!

I had a local shop build me up a custom setup. Out of the EM long tubes into 3” pipes, then to 3” high flow cats, and 3” X pipe, and finally finished it off with stock LT1 mufflers. All stainless except for the mufflers. They quoted me $400-450 but ended up charging $900 so I was not happy about that, all I could think was I could have had Corsa’s, but they did do all the work including putting in the headers so I guess I can not complain too much. I have not had it on a dyno yet but it sounds sweet, the stock mufflers kept the volume down right about where I wanted it but if they end up to restrictive they will be easy to change out latter.

Thats what id personally like to see you do Mike, i reckon its the best way myself. I put a full twin 2.5" system on my 87 from the stock headers to the back of the car and it cost me $400 AUD back about 6 years ago, i used mild steel mufflers then, but was only $30 a piece more for stainless, they just didnt have any on the day. Stainless pipe though.

Bent it all up right there and welded it in, cant go wrong.

Chris,

I have a beautiful 3" X-pipe too. I appreciate your offer do you believe the corsa 2.5 flows that much more than the restrictive factory 2.75?

I'm trying to Ed Wright to tune my car and if I'm still short, I may have to bite the bullet and go 3". But, I'll probably end up with resonance (something I currently do not have.)

That's what I'm worried about going to a shop and ending up spending more for an incomplete system than what an entire system costs.

Mike

You have a local shop with a mandrel bender?

Those are hard to come by.

If you don't, just buy some wide radius U bends or J bends from summit and have your shop cut sections out of them as needed and weld them in.

I have a 5"oval power tube with 2- 3" in/out to spintech mufflers on my 383

Quote:

They say it does as a whole but I don't know. I bought an L98 Corsa system and just used the mufflers and rear pipes. That was all I needed and it saved a bunch of money.
My front pipes came with my SW headers and I've been using a Magnaflow center muffler with an integral X-pipe. But I sold the SWs, R/T cats and connector pipes and will be reinstalling my DRM headers and Power Effects system again. It's 2.75" like the factory system but it's mandrel bent. I'll be keeping the Corsa mufflers and may still attach them to the rear of the PE system for street use. Even on the quietest setting, the PE mufflers resonate a little at certain RPMs. Not too bad, but a little.
I couldn't remember if you had an LTx or an L98 car. Since you've got an LTx car, you're not giving up so much as it currently is, but it could still be improved upon of course. Put that X-pipe in place of the resonator and I guaran-damn-tee you a SOTP difference in torque and response. It'll sound real good too, without being overbearing. If you want more yet, you can always install some less restrictive mufflers later on. But try this first and see how you like it. Having an LTx system to start with, you don't need to waste time and money piecing things together from what I've got.

The size of the pipe has nothing to do with resonance.

Quote:

then what does exactly?

I found I have gotten more resonance out of the several variations of a dual 3" system then I did with a 2.75" vborla system on the same car.

Quote:

Case is right, pipe size dosen't have any thing to do with resonance. There are many things that can cause it, lots of variables on the different systems. Muffler design, mounting, crossover or X, with/without headers, the relationship of the tips to the rear bumper.

Resonance is vibration, would the Flowmasters that everyone complains about resonate if the internals and shell were thicker (change the mass)? I don't know but it would be an interesting experiment.

Be that as it may, I've got a chambered catback system, no mufflers, on my LT1 with no resonance at all.

I disagree. Pipe size WILL effect resonance. If the pipe is too small, the velocity in the pipe will increase and that will cause sonic resonance.

As for performance, the factory cat back is rather good. It is more than large enough to support the power you want to generate. Too many "tuners" make the assumption that because it is factory, it is junk. Not true. Get some quality magnaflow mufflers and I think you will be satisfied.

There is no question that an x-pipe will help. Keep in mind that it will require removal of the resonator. To do it right, you need to test the exhaust with straight through pipes, get it hot and then hit it with a laser temp gun thing. The hot spot is where the X should go.

For 400 or so hp, 2.5" to 2.75" pipe will do great! no need for 3", to be honest. There comes a point of diminishing returns. The pipe is too big, the flow slows and so does scavenging, which will actually cost performance.

Guys,

This is from magnaflow is it valid or an attempt to sell exhausts?


Engine Size Horsepower Muffler Inlet / Outlet Size
Single Exhaust Dual Exhaust

150-200 CID 100 to 150 2" to 2-1/4" 2"
200-250 CID 100 to 200 2-1/4" to 2-1/2" 2" to 2-1/4"
250-300 CID 150 to 250 2-1/2" to 3" 2" to 2-1/2"
300-350 CID 200 to 350 2-1/2" to 3" 2-1/4" to 2-1/2"
350-400 CID 250 to 550 3" to 4" 2-1/2" to 3"

I decided to go with the B & B 3" stainless exhaust. I may delete the resonator and use a 3" X-pipe instead.

Anyone here using the B & B?



Mike

I can't speak for the later B&B, but the earlier one was prone to resonance.

I have Corsa... LOVE THEM. To me, the last 5 HP gained or lost from a catback isn't worth losing my hearing over!!!

My 383 while yet to see the rollers but on paper my combination should make north of 470HP at the flywheel. I've had Flowmaster and Magnaflow in the past and went back to the factory mufflers. I've since gone to Corsa and couldn't be happier (this is all with EM long tubes and their RT cat extension pipes). The grin on my face and seat-of-the-pants tells me the power left on the table won't be missed, and neither will the resonance.