I have a 1991 Firebird that I'm wanting to install a 4-point racing harness in. I know that I can get the bottom two belts bolted where the originals were, but as far as the top two, what can I strap them to?

I've checked my local laws and all they said is that you can't alter/modify the original manufacture seat belts. Well I still can get around that.

Anyway, where can I mount the two top straps and make it safe/legal? I'll also have passengers in the rear, so removing the back seats is not possible.

Thanks.