Side splitters are called 'canards', and in my opinion look a little silly. Ready2Play has 2 black ones on his car (in the pics above, the two black 'wings' sticking out on the sides of his front bumper).
The only functional rear diffuser I know of is from g-games.
I have both on my Tib, and were both hand built by me, i guess i should post some pictures up...lol...but i don't have any yet, i'll post some up soon. I don' like body kits too much so i decided that this was an easy alternative.
I am currently working on a rear diffuser as well that should be finished on the week-end if all goes well, then i will post some pictures up