Vortec350ss

iTrader: (20)

Interesting... maybe the larger pipe helps to dissipate heat better? Maybe a concern for towing. I wouldn't think that helps power where you need it while towing.

GRRR65GTO

I thought I read it was because its the same exhaust the 8.1 uses, and im guessing you couldnt get a 8.1 in a reg 2500

}BlueFire{

iTrader: (6)

My 2001 1500HD has 2.9" pipe to the cats then necks down to 2.75" to the muffler. After the muffler it's a single 2.75". I also believe it is the same exhaust the 8.1 uses. As in my opinion it is way too big for the 6.0.

Bama2door

Flopro 4" exhaust from DP back...

https://www.youtube.com/watch?v=KRbdGFDPRdM

whyt00

Dynomax 39379... I'm just sayin
Single - 4" Cat-Back System - Ultra Flo

G23crawler

Im running the factory true dual 3'' to a magnaflow 4'' out to a 5'' tip, probably one of the best sounding setups iv ever heard. Such a low tone its crazy.
[URL=http://s850.photobucket.com/user/g23crawler/media/image_zps61143372.jpg.html][/URL]

Sickrado21

Whats the part number on that magnaflow 4 inch catback?

TIMINATOR

The "lost bottom end" is usually one of two things, or both: you can feel the increase at the top end and mistake the stock low end where it doesn't yet need the flow, of being less (most likely,) or a tuning issue. Backpressure is bad! If, as the old wives tail was actually correct, and its not, then racers would all have an RPM adjustable "backpressure device" to enhance performance all across the range. No one does. It's been tried. Many times. As long as you have at least about a foot of pipe after the header or manifold, you are fine. The pipe the diameter of the manifold helps keep the velocity up, after that a bigger pipe helps the flow. GM got that right! They would have seen gains with a 3" manifold outlet, but the 8" or so 2 1/2" extension is good. Many dirt track stock class racers have removed everything after the manifold and found losses there. Also, having no pipe on the end of a muffler is bad too. About 10"+ of pipe after the muffler helps the scavenging and HP. Even a turndown helps. TIMINATOR