No no, you can still rice out a Si. I don't care what kind of car it is but once you start throwing on those stickers, lamo-rims, and other crap without doing anything that actually benefits the performance of the car is ricing it out.
I have seen plenty of riced out Si's. They would throw some lame-ass body kit on it, put a six-foot tall spoiler and 20" Rims and get spanked by my piece of crap 90 VW Jetta.