My headers bolts always need a 1/4 to 1/2 turn tightening after a good run. Is it advisable to Loctite (Red) them? Or Should I so for new stronger bolts?

i dont; think lock tight is the answer.

are they stretching? or just backing themselves out?

hex stainless bolts with lock washers. worked for me

Mine do that until they take a "set" and no longer need much attention. If they're recently installed keep after them and they'll settle down a bit.

If you can stand the heat snug them up just a bit when they are toasty. After some time they should stay put.

Thanks all. yes they are relatively new , So I'll give them some time to settle in.