I don't think this is entirely true. I beleive the 5th gen to be the grandfather that started off the craze...it was only after people were really modding the 5th gens that parts started to appear for the 4th.

That's not to say people were not modding 4th gens, but as far as starting the 'import' evolution' as you put it...5th gen rules

 

Dave thinks 4th gens rule the universe now, because he got a new paint job lol.