Matt P., the purpose of the side splitters is... uhmm, well they look really cool! Actually, they act as a large radiator fin that cools the side sills 100 - 200 degrees... okay, that's not true either, but after the stories about the headlight thingies I could sell that story! I believe the real purpose behind them is to smooth out the air that flows under the car at speed, and help create lower pressure. I think for our non-GTR type street cars it's more of an appearence piece which brings me back to... well they look really cool! The ones on my Blue/White GTS above are from PartsRack. Before painting them I did do some reinforcing on the sill/splitter assembly, because I was concerned about the strength at higher speeds.If you want, drop me an email, as I actually snapped a couple digitals of the underside where I did the reinforcement.