When you're starting out in drivers education, your stock seats and 3-way seat belts are fine. As skills grow, many will find themselves fighting to stay in their stock seats. So you might consider switching to another seat, and there's a gaggle of them available: With reclining or fixed backs, and steel, fiberglass, carbon fiber/kevlar, or aluminum construction.
If you want to keep the reclining feature in a side-bolstered cloth seat, one popular seat is the Recaro SRD, which runs around $600. OMP and others make similar seats. Kirkey recently introduced a non-reclining road racing seat in their line of aluminum seats, which is getting some good reviews, too. Seats, like helmets, all fit differently, so be sure you've sat in, and will be comfortable with whatever you get. If you plan to upgrade your seat belts to harnesses, make sure the new seat has, at a minimum, two harness guide holes in the shoulder area. In addition, some seats have standard, or as an extra cost option, another hole in the seat cushion for the sub strap (properly termed anti-submarine strap, as it keeps you from sliding under the lap belt).
There are several harness manufacturers, including M&R, Schroth, Simpson, AutoPro, and TRW. A 5 way harness set can run from $100 to $250. In harnesses you have four basic options: first, do you want a cam lock or a latch where the belts come together? Cam locks are more expensive than latch systems, and both have their proponents. Second, do you want a 5 way or 6 way harness? The variable is how you attach the sub strap - a single strap attached to the floor or a dual strap to bolts which are not thru the floor. Next is the strap mounting itself: bolt-in (permanent), wrap-around (to a rollbar/truss), and clip (to an eyebolt). If you use wrap-arounds for the shoulder straps, you'll still use either bolt-in or clips for the lap and sub belts. Clips are handy if you remove your belts in-between events. Last choice is color, as most come in black, blue, and red. Note that y-type shoulder straps and 4-way harnesses aren't used. If you don't have a rollbar to attach the shoulder straps to, you can either get a Brey-Krause Truss, a harness bar, or, on a 911, attach them through the rear firewall. The shoulder straps can attach directly to the BK Truss. Using a harness bar, the straps can go over (not attach to) the bar and typically connect to the rear seatbelt bolt location. If you attach them to the rear firewall, you'll need to use steel plating to reinforce the area the eyebolt mounts to. You can look over the PCA Club Racing harness guidelines in safety: rule 13, and appendix B, for additional details on mounting your harness.
Written by Bill Gregory for the "Challenge", monthly publication of the Connecticut Valley Region, Porsche Club of America.