I run 3" straight back to a 3" magnaflow, it has worked good for me. If you are going to get a duramax exhaust i would get the one off of summit for ~$270. PM sent.

 

anyone have any videos of their exhaust???

 

 

BTW, I plan on running 3" DP into a 4" bully dog muffler and a stock d-max exhaust tip...but I would like to hear some clips of other folks exhausts...

 

The dyno video in my sig is the 3" magnaflow, you have to crank up the volume to hear it though. I'm sure someone will chime in with a good vid.

 

Well, I think it depends on how much boost you plan to run and how quiet you want it to be when out of boost. Personally I like it as quite as possible when just driving around which is why I have a stock 2500HD muffler. And I can boost up to about 6lbs before I have to open my cut-outs for anything over that.

Here's with a cut-out open.
http://www.youtube.com/watch?v=Qzp3-pUavkU

 

hahahaa..i love it i will def get a cut out. what size is yours spoolin? how much comp. is your motor? i have talked to everyone and they say im ok. but i want to run 13 psi or so on 10.2:1....

spoolin also what kind of blowoff do you run? love the sound it makes.

im running a tial 50mm, and a 44 gate.

 

If you were referring to me, I have the TurboSmart Race Port (50mm) bov. I had a 38mm before, but i upgraded to help with compressor surge.
Not trying to hijack your thread, but do you see any difference in power with the cutout open Spoolin?

 

The Cutout is a 3" Doug's electric, I prefer them over the butterfly ones as they don't chatter and seal very well. My motor is at around 9.0 compression maybe less, it's good for boost obviously but the lower the compression the more noticeable your cam choice becomes so make sure you find the right cam for your set-up. Too much reverse split on a low compression engine will make your truck a dog down low. On a 10.2:1 engine I wouldn't go much more than 10-12lbs with 91 and meth. Keep a sharp eye on your tuning, get a wideband for sure. If you run better fuel than you'll be safer. I know one guy who rides around on 100 octane for that exact reason.
As far as the blowoff it's a Tial(forgot the size) but basically the stronger the spring the more chirping it will do, the weaker the spring the more it will sound like the Fast and Furious.


Because of the way I set my truck up there is a big difference yes. And in most turbo systems you'll see a couple psi difference with a cut-out depending on what kind of exhaust you have and where you place the cut-out. Because I wanted a real quiet truck when in traffic and around cops I stuck with a stock muffler which doesn't allow too much pressure differential accross the turbine. But with the cut-out 6" from the turbo outlet and before the cats and muffler I go from a max of 7psi with it closed to 18psi+ with it open. And obviously the power is very different...as you can imagine, it's about 400hp/tq difference but my set-up is extreme. My truck doesn't really wake up until I hit about 10lbs of boost anyways... again, cam choice is critical on low compression engines.

 

I run a 3.5 pipe out the side past the turbo. Any muffler I tried was a restriction and hindered flow. Its NOT that loud. I vote NO muffler