chrome wheels

I have a 2001 mustang coupe and I was thinking about getting chrome wheels. I haven't decided if I should get 17s or 18s. My uncle works at a Ford dealer and he said that 17s were the highest that a mustang could have. Is this true or can a mustang handle and turn well with 18s? Your help is greatly appreciated!

Saleen has been mounting 18's on their cars since 94. I don't know how good of a ride quality you'll get though on a stock coupe with 18's.

Rousch slaps 18s on his cars also.