Ok folks I started with 2006 granite with ami 370hp 13 sp fuller and 4.17 mack rears that I called the "boat anchor" when I first bought it. Hauling road construction materials, heavy equipment, and grain so loads vary from 70,000 to 85000 lbs. sluggish, no low end tourque, terrible fuel millage, and just tough to drive in the hills was a far cry from my old ch with a 400 or even my old r models with 350. So I went to work on here and learned how to make these trucks run. My first step was to take my 370 to 427, which I did in by having my local injector shop resize the injectors and then drove to local mack dealership to have it set to 427. Results...better definitely than before and was somewhat ok with how it ran so I ran it all season that way. This fall I decided to go a little further and do the conversion that macktechnician has done on here. I however started in reverse order to see what would happen. I started by leaving everything alone and putting the full 5'' exhaust system on and noticed no real difference other than it sounded a lot better with the flow threw muffler. Next I installed the etech manifold and the s 400 turbo and noticed a little bit of pick up but not much at all. also boost went from 32lbs to 30lbs when doing so. Finally I installed the injectors from mike at k and s. The truck is now a completely different truck. Low end tourque and lug is back where its supposed to be, power is awesome when you need it but the thing that I find most impressive about it is just how easy the engine has to work now obviously less pedal and less work to drive. Less shifting. As far as millage goes it definitely didn't go down any doing some of the same runs as before but that's hard to tell this time of year with winter time fuel and heavier loads. An amazing, relatively inexpensive(I figure I had $2000 in parts, I got a turbo dirt cheap) creation that anyone that knows anything about trucks can do in there own shop. Mach technician has done a great job of listing part numbers, pictures, and information on this topic. with out this a lot of us would be still unhappy campers and cussing mack every day! thanks again!