I had some on a 5.0 a few years back and I never had to re-tighten them after I initially installed them. These were the kind that had a tab and E-clip.
Can't imagine that you could use them on a small block mopar, at least not on all the bolts. The bolts are very close to the tubes and you normally have to use bolts with a reduced head size just to get them in.
In anycase I have never had an issue with header bolts coming loose.
I've heard of using the Ultra Copper on the GASKETS to seal `em up nicely. I've never heard of using it on the threads tho.... Plus if your using a quality header with a thick flange you'll have less issues with leaks. Cutting the flange between the tubes seems to help *some* people with leaks that are running thin flanges.
Or just keep the wrench in your glove box and get used to it.... :happy4:
I have a pair of tti headers, didn't know whether or not the bolts losen up alot or not. I guess the locking header bolts are just a passing thought in my mind.