with the exception of the H series any of the other common swaps are pretty routine except you have to buy mount kits and linkage to make them fit in the 4th gens. WE don't get as much cosmetic support as the 5th gens but peformance wise its all about the same. I would suggest getting a rex I don't have one but when I find a clean one I will try and get. The rex guys in here will tell you how much fun they are. If your planning to do a swap you should be able to find a non running rex or hatch for cheap. www.thepartstrader.com is a nice place to look. Good luck on your search...........