Originally Posted by Charlie_santos
You lose back pressure with that and with no back pressure you lose HP
depends on the car? These 5.0s don't seem to have that problem. Everyone says taking the cats off won't gain any HP, might even loose some from loss in back pressure, yet people are getting 15-20 HP gains doing this. I felt the gains immediately when I did this. I know this because I also spun the car out on a turn because I drove her like I normally would and didn't account for the gains!
I don't think I have seen anyone straight back a 5.0 yet. If someone is going to do it, they need to before and after Dyno!