I am thankful I found this site before spending money on useless mods. that sound like they will improve performance. I had a 95 XJ that I put a K&N cold air filter on, throttle body spacer, etc. and did not repeat the mistakes with my 2004 TJ. Thanks to Jerry Bransford, Chris and all those who shared their info./experience. Now I can spend money on those mods. that definitely improve performance like re-gearing.