hesitation - it was the cats I have a 2005 mustang gt with a saleen supercharger 39lb injectors,no cats,90mm MAF,5 speed,custom tune by HPP. HT0 sparkplugs, shorty headers, 10lbs of boost. I have been running this combo for a few months & about 3k miles with zero problems. best guess - the cats started to get clogged since i took them off and after letting the computer re learn they were not on anymore - no problem.
