You should MOST DEFINATELY be using anti-sieze on the threads. It doesn't make your spark plugs back out so it won't make your fasteners back out. (you are using it on your plugs right?) Anti-sieze is way cheaper than having to pull your heads and have them tapped for helicoils and replacing the head gaskets. Use it any time you use a steel fastener on an aluminum part.

Split type lock washers should stop the loosening. Studs are awesome because they go from course thread to fine thread which has better torque retention and vibration resistence. If you want the ultimate in torque retention you could always get bolts drilled for safety wire like the NASCAR and other racing guys do. If you do it right, the bolts CAN NOT MOVE. If your scared of lockwire then you can try Stage 8's locking bolts. They're pricey but they can't back out unless you disassemble them.

You have options. I like the mechanically locking hardware around high heat. Metal won't melt, plastic and chemicals will.

Try some new Grade 8 bolts and split lock washers first. That shouldn't cost more than $10.