HSVKLR: I fitted my FMIC myself also with a mate helping. Providing you get a good bolt on japanese or quality local made kit you wont have any dramas. The trickiest thing was trimming the front bar to suit, and cutting the 3 inch hole in the sidewall for the cooler plumbing, other than that, as mentioned just remove any piping etc thats no longer required and the new gear bolts into place.
PM MIC33R as he fitted an HKS kit to his R33 himself and documented the install with photos which might come in handy for you.
Hope this helps.
Nick