speed density car and just upgraded exhaust to bbk headers, bbk off-road h pipe, and 2.5" flowmaster cat-back. now the car misses unless i hammer it and i get a hesitation until i reach 2000-2500 rpms. it almost feels like i have some sort of power-adder that kicks in at that rpm range and i don't like it. i'm wanting to get back to a smooth running car, any ideas?