I have an 02 wrx sedan and if I switch out my oem intercooler for and xs-power or perrin top mount, is there anything else needed to be changed out, such as injectors, bypass valves or anything else?

 

nope but you may want to have it tuned or you will have more turbo lag because of the larger top mount... I have the turbo xs and love it

 

If you're still running the stock TD04, then you dont really need a upgraded top mount. Matter of fact, I know quite a few people running VF series turbos on the stock TMIC and still making good power.

 

but you'll have an issue of heatsoaking and not get all the horsepower out of your setup in that case.

 

I have the esx tmic and it works great. I also have upgraded injectors/plugs/fuel pump, but when I didn't have them in I did notice that the car felt like it had some more power. I'm not sure how big the other ICs you listed are, but the esx tmic is about a few inches wider than stock and twice as thick. The stock IC just looks like a baby to it... :-P