I think with all else being equal, if he's got the banks product on his truck and you've got Eric's tunes I think you're 6.0 will be quicker. If the Dmax had "real" tuning you'd be in trouble. I've ran my truck against a coworkers '03 crew cab short box Dmax with a 6 gun and I walked all over him. I'd say just race him, be safe and have fun...
