I'd day Stick with Yellow... it looked the best...

Also, the very front where the air goes inside teh car, try making it a Mesh or some kind of HEX pattern... right now it looks solid and there is no point of it if it's not letter air in

Hmm... what else... I was going to tell you to maybe put on a top scoop but if it's an SI then the overhead opening is there

also dont forget to pu on the gas cap

-Emo