ok i just swapped a 5.3 to a 6.0 LQ9 at almost 3/4 throttle i hit 6k rpms but it acts like it cuts out.. thinking i could be hitting the rev limiter but not foresure.. i hope not cause i have alot of peddle left, and if this is the case i will have to ask allen for another retune ... unless i get lucky and melissa hasnt sent the other out today ..