go ahead and try the cg lock and all the other gizmo's that claim to hold you in better...

then try what works and what pro drivers teach:
slide the seat back a few inches, buckle up, pull the belts all the way out to lock it and slowly let it in till its where you want it, then slide the seat up. that will hold you in place the correct way.

btw: the slide back and forth technique is the proper way to buckle in with race restraints also...

imo, 4 pt harnesses are dangerous and should be outlawed. you still have a street car so use the safety gear that was designed for a street car.