Hehe

Going 15 - 17 shouldnt really decrease performace unless you go with a really heavy rim...it will most likely just give better handling with only a very minor derease in all other areas bar looks =)

Before you put your 17's on,wiegh the rims with and without tires,wiegh the stock 15's(rim+tire)...let me know the wieghts and how the 17's feel are compared to the 15's!,would be interesting to know =)



Cheers,
Paul