99 2500

This 2014 looks like it's vibration free past 140 mph http://www.performancetrucks.net/forums/gmt-k2xx-trucks-general-discussion-221/140mph-2014-5-3-run-523132/

What performance gain did you see? I got .2 seconds reduction on 0-60 on my G-tech meter, this is going from a single large magnaflow 22" case lenght with two 2.5" inlets and one 3.5" outlet to the dual 2.5" Dynomax mufflers. The funny thing is that it's quieter too and a more refined deep sound than a loud raspy sound.

I have dynomax ultra flo ss mufflers on my 1999 6.0l and would not trade the sound or performance for any of the previous mufflers I had on ( flowmaster, magnaflow ). They are the offset inlet and center outlet part number 17289, quiet up to 3000 rpm's with deep powerful sound after 3000 rpm.