big rims CAN slow the car down... it depends on alot of things
weight being number one... overall diameter of rim/tire assembly being number 2
i think 18's look great on SN's and foxes can get away with 18's as well. The only Mustang i think that can hold bigger are the 05+
its all in your opinion though... whatever you like.
...as long as you know the consequences of putting heavy 20's on a Mustang.
