you cant not use those guys.... they have to be hardened due to the extreme heat from the exh... autozone carries multiple length 5/16 course (head side) and 5/16 fine (nut side) in different lengths... i can remember what size i decided worked best bt i think it was 1.5" OAL.
also make sure to get the hardened nuts (gold colored), the set runs about 50 bucks
