when you drive out the studs, you will see that they have splines near the base. that is what holds them in place. make sure to leave a nut on and smack the nut to drive them out. now (with the nut on) place the nut end in a vice so the bolt can spin. put a cutoff wheel on a grinder and carefully grind off the splines until teh bolt will just barely go back into the hole all the way. now you turned your press-in studs into bolts and kept it all OEM.

Scott Landon
1995 T100 - total buildup underway
1988 4Runner (22RE, W56) - new DD
2005 Dodge CTD 4x4 - Tow Beast
1990 Spec Miata
2010 GT3
2013 E92 M3