Any idea how tight exhaust clamps should be? They don't really seem to tighten up, and I don't want to over-do it. It's on a 1-3/4" diameter pipe and the clamps have 3/8" NC threads. I've got somewhere around 15-20 ft-lb on the u-bolts right now, and I used anti-seize on the threads. I used that muffler cement so I'm hoping it's a good seal as-is, but suggestions are appreciated!