I know I have Belanger headers no cats [******] airbox. But It should feel close because of the extra 50hp. I am sure once it is broken in the car will run better. On the low end is where I feel the differnce the most. My GTS with just headers made 452rwhp and 512rwt on button 652 and 814. What are the SRT's running to the wheels stock and then with headers and exhaust?