I have 20s on my 03 Turbo. The sidewalls are so incredibly thin that going over any significant pothole will bend the rim so you have to be very careful. There was also some rub when driving at the limit. While on the track I went through the wheel well liners and I have stock suspension. I like the look and whatnot but if I had to do it again I think I would go with 19s.

 

IMHO I think 20 inch rims on our cars is too big. I'm running stock 19 inch 997tt rims on my car and I wouldn't go any larger.

 

I personally don't want wheel hop from not having enough sidewall with 20" and also 19" that I'd rather stay with my 18".