How often do you plan on tracking the car?
If it's just a few times a year, upgrade the brakes and install some decent coilovers. throw some good tires on it and call it a day.

If you're tracking it a few times a month, buy yourself a cheap track toy like a Miata or an S13/S14. for the money you'd spend modding the G, you can buy the whole car AND put some decent mods on it and run faster lap times.
I've got under $6000 total in my 240SX (including purchase price) and keep up with the average Spec Miata on the track.

and there's no electronic nannies on either of them to get in your way. If you're a good driver, lap times will reflect it. If you're not.. well....

 

With you in the seat, push your seat back a couple of inches. Insert the belt into the slot and yank hard and quickly to get the crash mechanism to lock the belt. Push the seat back up and the belt should be tight on your body and will hold you in place. If it's too loose, keep trying until you get the belt length you need.

 

I would just swap it out for a good race seat. The seat doesn't take long to change back and forth and there is no good replacement for a true race seat. Even my coupe seats suck when it comes to true track driving.