17" porsche twisties are goin on, but what about fender width???

[VRSICK]

I just purchased a set of 993 brakes, rotors and all. I think the fuchs that I have are too small for these brakes, so i'm going to go for the 17" porsche twisty wheels. I love the way they look, and plus they look good against a silver paint. My question is this...

I'm not sure how much wider, if at all, I should make my fenders. The sizes are 17x7 and 17x9, and I like it when the wheel goes right out to the fender. People have told me in person that i'd need a 1/2 inch wider in the rear, and the fronts are ok as is, but i'd rather ask you guys, since you seem to know more about this type of thing. If you hvae any questions that would help answer my question, PLEASE ask away. I am sort of a newbie at this, but i'm trying t learn as fast as possible.

Thanx in advance
-Mike