Adam,
Experience(!) has shown header bolts to be problematic - as in: they vibrate loose and back off, even falling out on occasion.
Similarly, lockwashers can be hit and miss. Sometimes they too fall out.
I ended up putting these on more than 30K miles ago - no regrets, no loosening:
https://www.jegs.com/p/Stage-8/Stage...49275/10002/-1
I had to modify a few of them to clear the header primary tubes by grinding a relief in them. Otherwise not too hard to install.
Hope this helps,
Tom