Tamper SCREW or "Fancy Rivet" (silly question of the day?}

[ericp351]

Hi all, "new Guy" type question. Have an A2 with the small turbo Cummings. Like to be able to adjust max fuel, and maybe install exhaust pyros some day. Question- are those little "tamper resistant" (bosh) screws, or fancy pop rivets? I ask as one resisted my cut slot and screwdriver and is now mangled. Screw or rivet may factor into my tap size selecting and all as I don't want to disable rig as I hunt for metric stuff. Thanks. Post script- The "regular cover screw" was never removed and was very tight. May have had Locktight. Does that sound right?