Spoke with Magnaflow tech. Based on that and engineermike's comments I'm gonna use a Magnaflow either 3.5" or 4" system. Should be a minimal restriction since its a straight through design.

 

lol well, at 700RWHP ... That could kinda be expected.

How bad was it? Just curious?

I am trying ot figure out what i want to do now, for my soon-to-be blower car. It will only be on about 7PSI until I build me a forged shortblock but ...

Thinking of taking the catback off, running some type of small, unrestrictive, straight-through on it, and dumping it, at the rear axle. Catback only going on for I&E ... Since my boss wouldnt sticker it for me I dont think, with it dumped at the rear axle.

 

It's hard to say, exactly, because the boost level on a turbo is backpressure dependent. Remove some backpressure and the turbine speeds up and makes more boost. I can tell you this, though - at 700+ rwhp, when I removed an Aerochamber and installed a Magnaflow, the boost went from 18 psi to 24 psi with no adjustments to the boost controller. Also, the endwall on the inlet of the Aerochamber was bulged out from internal pressure and heat.

Mike

 

What kind of magnaflow are you running now? Just a regular magnoflow catback, or some custom set up?

If it was the catback, I have to say, WOW. I never realized they had that kind of free-flow advantage ...

 

also remember that every bend the exhaust goes through is a restriction. something exitting in front of the rear end will most likely make more power than a rear exit catback.

 

Mufflex 3.5" piping with a Magnaflow muffler. The 12909 bolts right into the Mufflex piping with no modifications. I'd say that this exhaust combo would be hard to beat.

 

I originally planned to run a 4" Mufflex with a Spintech dual exit, but since my tank is sumped, the option of running any traditional 4th gen F-car exhaust system went away.

I ended up using the Mufflex 4" stuff, but run a single 4" exiting out the back with two bullet mufflers in line and a turn down now.

 

Hmm ... I am really impressed. I wonder what the difference would be between that, and a magnaflow muffler on 3" piping ...

Its gotta choke it up a good bit more.

I think I am going to get some sort of free flowing single muffler, and hook it up at the Y, then single pippe dumped at the axle.

 

Saw this setup for some of you:

http://www.ls1tech.com/forums/showthread.php?t=585223

 

Im gonna make a custom "LM" for my car. They have 3" to dual 2 1/4 im gonna have a 4" off the downpipe to dual 3" pipes. Shouldnt be as loud as my car was with long tubes and the normal LM since its going through a turbo now

 

Not sure if this is a good comparisin but I originally had a magnaflow 3 inch system on my car. It was so loud it made me sick.

I have had a mufflex 4 inch with the spinteck muffler for 2 years, running through 2 3 inch magnaflow cats its just loud enough to live with. I had to change exhaust just so I could drive the car.

Have not run car without exhaust but through cats it made 657hp 590tq at wheels.

John

 

John, Which Mufflex system are you using? Single 4" outlet or the dual 3" outlet?

 

i am running GMMG on mine

 

Dual outlet 3", car is louder at the front than the back ever since I put the T trim on.

Originally with the magnaflow I had to make sure I was coasting if I drove past anyone that could give me a ticket.

John

 

Purchased a mufflex 3 1/2 system with a spin-tech single outlet. There was alot of back pressure and the pipe was blown off many times (383/ D1/ 72# injectors). So, I made my own pipe with a QTP cutout dump @ the right rear seat area. I retained all of the mufflex down stream stuff. That solved the back-pressure problem. The engine would just not rev with all that restriction. Still run the spin-tech when I want to be real quiet. Spin-tech did not work well with the blower.