Last Saturday I had 4.10's installed on my stage 2 roush. I noticed an increase in pickup from the hole, which I was happy about. So yesterday I had a High flow x pipe installed and the sound was conciderably louder. BUT, It seems to me that my car is slower. Now I dont know if I am going crazy or maybe it is because the car is so much louder, but I am kind of confused on why it seems to have lost power with the high flow cats. Has anybody else noticed something similar to this or am I losing my mind. Any thoughts would be appreciated.