Add interestum,
I just made up a word...Drilling a lateral hole in the bolt head like you are explaining is commonly done on full size aircraft. This method is truly the best way to keep muffler bolts from working their way out-IMHO. However, if the bolt heads are recessed into the muffler body then this method is not possible.
Last edited by Steve S. Helland; 09-19-2018 at 07:23 PM.