stainless steel hex bolts and lock washers. Stuck with the orginal bolts on the intakes -- wanted them to fit correctly with the nylon (crush) washer. Those intake VC bolts are only under lite torque, so it's pretty hard to strip them out.
Should also plan to replace those nylon washers when you do this job...
FYI -- Hopefully you know the trick about applying extra liquid gasket to the exhaust VC inside corners? If not - I can explain further...