I think I heard the stock fuel injectors were good for about 145-150 wheel horse power. Im pretty sure that is right. So when you run out of leway with the 19lb injectors and switch to a larger lb, you would have to either recalibrate your maf or go with a pro-m or something along those line. I picked up some svt-f injectors (30lb) and I am going to just by a used maf somewhere to fix my problems