RE: Exhaust screws.
If you have socket head screws you can drill a hole thru the head. If you don't feel like doing that hit the yellow pages for a fastner supply shop such as fastenal or even grainger. You might also try microfasteners.com. The lock wire works best thread lock will work but what happens when you want to remove the muffler?? You don't need a pair of safety wire pliers it can be done by hand. If you have any questions stop by your local aircraft mx shop the mechs will be more than happy to help.