Im thinking of getting some JBA spark plug wires but there are two choices. 8 mm & 9 mm. Doe's anyone know the difference between the two performance wise? Would it be ok to go with the 9 mm?

 

Performance wise? none.
Performance over stock? none
Its basically just a look thing.

Now if you upgraded your whole ingition system, the difference between stock ones and jba 9mm, might give u a couple HP (1-3 i would guess)