Won't work. Trifecta has to be completely removed or hp tuners won't work. Not even the gm tool at the dealership will take out trifecta. It has to be done with the trifecta cable. I learned the hard way. Paid to have it reflashed to stock at chevy and hp tuners still picked up the trifecta tune. Hptuners doesn't recognize the ecm with trifecta.