Well, the exhaust is very good, as quiet as the original, inside or outside.
I used a 4" outlet, quiet Donaldson muffler with an attenuation rating of 12-18 dBa (quite good) with a low rated restriction of 1" Hg (1/2 psi) at 1000 CFM (I calculated that it is about what the engine produce at maximum horsepower).
I can really feel that the engine is stronger and breathing better especially in the higher RPM.
My system is custom, I made it with selected parts. If you want some hints at how to do it, I can give you the info. The vans are different than the trucks and you have to use a different approch to the exhaust system. A kit with stainless steel pipes in on the way.
The Montreal's Hummer dealer has 3 chromed 6.5 TD emblem in stock if you have difficulty getting them.Edited by: Richard7