I have used them in 3-4 cars with no issue But the big problem is the retarded chips MSD sells , fist you have to buy 5 not the 1 you need & second the chips are commonly mismarked , I was dynoing a car last fall with a 6200 chip in it & it would kill off at 5200 everytime , I pulled the chip & she ran clean past 6200 immediatly