I'm new to the duramax world so be easy on me but I've got a buddy who ha his 08 SilveradoHD chipped, hes not sure what kind he bought it that way, but all I know is it hauls ass down the road and leaves mines in a cloud of smoke. The only real thing I know about the set up is that he has 3 fuel injectors on it one under the hood and two tucked under the driver side rear wheel well. Any odeas what this may be or any recommendations of what brand will help me increase horsepower and torque? Appreciate any info and ideas.