RE: mufller bolts
An Allen bolt is around 44 Rockwell C scale so they are pretty hard. They have to be drilled in a guide jig.
Best to buy them already drilled
http://cgi.ebay.com/ebaymotors/AIRCRAFT-AVIATION-TOOL-SAFETY-WIRE-DRILL-JIG-NEW!_W0QQitemZ290327936912QQcmdZViewItemQQimsxZ200 90703?IMSfp=TL0907031710004r9630