gr 8 bolts for me, never had a problem. I wouldn't mind running studs, but bolts are just easier to find. If you change your suspension set up frequently, finding new studs at the correct length (assuming you can't make your own!) can be a PITA. I can drive 5 mins to the hardware place and get bolts of the right length. It would be cool if ARP make some longer-than-stock replacement studs for this application... the steel they use for their hardware pretty much kicks ass.
j