[Don Plumley]

Ultimately it's your personal safety and what you feel comfortable with (any GCR's notwithstanding). For me, I'm not comfortable using seat mounting hardware for seat belts - it's a single point of failure. If I'm in a bad crash and my seat rips out from the floor, I don't want my seat belts coming out then too. Yes, I know that factory belts often attach to the seat.

For the lap belts, why aren't you using the stock belt mounting points? You can use rated eye bolts with longer shanks to preserve the stock belt mounts. The problem with using seat frame holes is the angle of the belt. Have a look at the Schroth installation guide (online) and see what they recommend.

For the sub belt, there are braces that attach to the seat frame holes (under the rails) and provide either a one or two position mount. The trick is to get it far back enough - you want at least 20 deg from vertical.