I have a shit load of those bolts sitting around my garage lol...it's nice to know they aren't cheap...I'll sell you them $5 a piece just kidding.

I usually tighten until I see the rubber start to squish out barely on the little washer gaskets that go under the silver nuts. After about a week of driving I go back in and give them just another TINY twist. That usually seats the gaskets really well. Also, CLEAN CLEAN CLEAN the surfaces from ALL residue before installing the gasket. You DO NOT need liquid gasket for this job if you clean and prep the surface the correct way.