Originally Posted by kanyonkid

im not sure, but i run the RRE STEALTH 3" exhaust with an open dump... thats the quietest exhaust u can get. no drone on the highway and very quiet around town

Originally Posted by pal215

hahahah what he said ^

Originally Posted by BenJ

You're missing the main point of a 3" TBE, which is to limit the backpressure created by a more restrictive setup such as the stock exhaust. Regardless of an O2 dump or not, a 3" free flowing TBE will be beneficial in a turbocharged application. The only reason that I can see for running a smaller diameter exhaust would be to either meet the needs of a particular racing body or to manipulate the turbo's powerband. Secondly, the only currently available stock frame turbo that will meet your specification of 550whp on a mustang dyno would be an FP Black realistically unless you feel like pushing a Red beyond the limits of everyday practicability. Third, the best way to meet your requirements of a quieter exhaust except at WOT would be to incorporate either a different muffler or add an additional resonator to your existing setup. To figure out the exact size of the exhaust needed to compensate for the addition of an O2 dump would require you to specify which turbo you will be running and from there finding its flow rate at a given pressure that you will be testing it at and then factoring in the orifice diameter of the wastegate opening and the amount of pressure that it would be able to expel...or something like that.

Originally Posted by davidbuschur

Dang I hate adding anything good here anymore but this is an intersting subject that I've done tons of testing on.

In 2003 we did exhaust testing, hard to even find it now. First we did the axle back, car gained power, then we did the downpipe, car gained no power, then we did an offroad pipe, car gained more power, then we put the stock downpipe back on and lost power, put the new downpipe back on, gained power. The only part left ont the car stock was the stock mid pipe between the cat and the muffler. We had built everything out of 2.5" mandrel bent tubing up to that point. I don't remember how much power the car was making at the time, over 300 on our old Dynojet I'd guess. Then we replaced that one last section of stock turbing with a 2.5" section and the car made some rediculous gains in power, I am thinking over 20 whp. The factory resonators are VERY restrictive.

We then of course built our 3" system, tested it against the 2.5" and stock. The 3" worked the best throughout the entire RPM range. The 2.5" vs 3" downpipe made no difference in power then, I'd say the power levels then were under 400 whp the last testing we did on 2.5" vs 3" downpipes.

Flash forward to about 2 years ago. I had the lighest 3.5" tubing with minimal bends in it bent up for a 3.5" turbo back system to market. I built one for my car, the Bad Bish, put it all together using V-band connections and a Burns super lightweight racing muffler. Loaded the car on the dyno and dyno'd the car back to back VS our 3" turbo back with our bullet muffler. The car was over 600 whp on our Mustang Dyno at the time. The results? 3" had more low/mid and the same or better top end. I could not believe it. I had all those exhausts left at our shop until about 6 months ago when I traded them to another shop looking to build some. I built one for Al's GT42r car, one for Matt's GT42r car and sold the one I built for my car.

To add even more to this. I think it was this spring when I decided that my 700 whp car was just too loud and I was sick of listening to it. The car had run (most of you know this already) 9.0 at 159.6 mph through our standard 3" turbo back with the bullet muffler. I found a small diameter lightweight muffler that I wanted to try to run in the rear. My car runs our Bullet muffler in the center where the cat goes because of the JDM EVO9 rear bumper cover, I don't like to see a big muffler back there. This new muffler I found was very small in diameter, we named it the SD muffler (small diameter). I kept the bullet in the center and added the SD muffler to the rear, it took a bunch of the noise out of the exhaust. Anyway, the car was on the dyno, never unstrapped. I made a couple of pulls with the car that were in the 69x whp ran and then we swapped on the SD, the power went to 700.

Some of what I have seen makes no sense but the dyno doesn't lie and you can gauranfkingtee that if I am testing stuff like this for my own use and my own car there is no BS being pulled, I want my car to be as fast as it can be. To this day I run our complete 3" turbo back, bullet in the center and SD in the rear. The car has made 710 whp like that now on our dyno.

My car also runs a 44 mm Tial external gate that of course dumps some exhaust out the front of the car under boost, definetely beneficial. The odd thing with this is the stock style 02 housings that do the same thing...........I've seen nothing but losses from.

Maybe Myth busters need to buy a dyno. haha