im new to a duramax and am kind of lost. i recently bought a truck from a dealership and ofcourse they dont know anything about it. the truck is fleece tuned using efi live and has the dsp5 switch w lope tune. it has a 68mm vgt turbo from fleece i do know that, but on the hot tune when i stand on it bottom end pulls hard but when it get higher rpm under wide open throttle it really doesnt pull at all and falls on its face....ive done a bit of reading on here and am under the impression it might need a lift pump? fleece said it should be around 550-600hp but i seriously think the way it is right now id get beat by ab anything :help HELP!!