ok ok, it's a 2k3 2500HD, Duramax Diesel matted to a Allison 5 speed auto putting power down through an american axle and MFG 11.5" rear end. If you search, it is very easy to hit high 13's low 14's with just a programer and exhaust on these trucks. Everything else is factory (Injectors, turbo, heads, etc).