I'm just wondering if a second or third gen throttle body would fit my car and work with any performance gains whatsoever.

 

The bolt pattern as well as holes for the primary and secondary butterflies differs between the GSL-SE and 2nd Gen, so therefore, you'd probably need to do some sorta grinding and filling to get it in there. There may be some gain to be had since the 2nd gen throttle body is larger, however you need to get that air past the GSL-SE's more restrictive air flow meter first.