Looking for advice...

Several times my exhaust manifold bolts have come loose and I have even lost a few despite torquing them to specs and replacing the gaskets with FelPros.

What do you guys do to keep them from coming loose and is there a brand you would recommend for a quality replacement?

Would new grade 8 bolts from the hardware store be sufficient?

Do the spacers that come on the bolts from the factory factor play a part in keeping the bolts from coming loose? Should they be replaced?

A quick response would be appreciated as I would like to order them today so I can have them for the weekend.

Jeff