The computer is different, so the harness is different, you will DEFINITELY need a donor vehicle, or at the least, a cooperative junk yard with a 16v to get EVERYTHING from. Computer and wiring harness.. It's a bitch, and usually easier to just find a wrecked 16v. I wanted to do this myself. but the gains weren't worth the price. It ended up being cheaper to sell my 8v Track and buy a 16v Track. I didn't do it. I just kept the 8v.. too much hassle.
Still looking for a decent 16v but the prices are rising fast!! These kicks are good investments when you can find them under a grand, JUMP ON EM!!