This may be a little off the wall, but..

I do not like the idea of using a roll cage for daily driving, but would like to use a 5 point harness at the autocross and track. Has anyone tried to fit a single bar from one seat belt shoulder bolt to the other and then connecting the harness to the bar?

I have an 04 and the upper seat belt bolt is on the outside of the roll hoop just above shoulder height. If one could manufacture a bar that bolts up at one hoop and goes behind the seat to the other hoop then a harness could be used without losing use of the OEM seat belt.

 

not that I know of on an S, but my buddie just put one in his NSX, so Im sure it can be fabricated somehow....

Dont forget though, you have to get around the center glovebox somehow, unless you want to drill holes through it...

 

The only problem is if you have harnesses and no rollbar you won't pass tech.

 

You do not want to run harnesses without an aftermarket rollbar or cage. With the stock seat belts your body can move in the case of a rollover. Unless you're a midget your head is probably at about the same height or higher than the stock rollhoops. With a 5 point harness you aren't moving anywhere and it's likely your head will be the first thing to smack the ground in a rollover.