i just fixed this today.
does the boom come from the intake or from the wheels.

if it comes from the intake. u need new spark plug wires. spark plugs. this fixed the problem its alot better now. but i still get a little stumble, barely noticeable to anyone other then me. i guess i need to change the inginition coil as well.

Experience is the worst teacher; it gives the test before presenting the lesson. Why do you need the cats when u have dogs 04 WRX - TOTALED 3-5-05 Previoius Owned: 96 Contour LX with svt kit