If you are using the right length studs then stock 13mm headed bolts will work fine. Some stud kits had too long studs in which case you needed a 10mm headed bolt and it is a pain in the butt to line them up.
Actually I figured out my solution. I used HELP! part #03411 and lock washers to clear my head nuts and bolt down my BBK longtubes. Thanks for your imput
Rick