Harness safety in street car?

[Peter Jackson]

I know that installing a 5 pt race harness with stock seats is bad.
The downward angle of the rear straps will compress the spine in an
accident.
I know there are Y harnesses designed for use with the rear shoulder
belt mounting point. Are these OK because of the rip stitching or
because the angle is upward?
They sell partial roll bars that are mounted far enough behind the front
seat that your head wouldn't impact it in an accident on the street. The
stated purpose is to provide a belt bar that would change the angle of
the shoulder straps so that they come off your shoulders at an upward
angle, go over the bar and then angle down to the rear seat mounts.

What is the full story?

My goal is to have a harness I could snap in for track events only but
to have mounting point hardware I could just leave that would be OK for
the street. I don't want a full roll bar but a partial loop/bar in the
back seat would be OK.

Peter J
96 SE-R