CoralDoc

One non-trivial problem is the correct attachment of the shoulder straps to the car.
Read this thread, do some additional research, and then decide if you think it's safe to use a 4-point harness with stock roll hoops.

Triple-H

Wise words...

The Reverend

I agree with Mike's post: either get a rollbar, a proper seat, and a 5 or 6 point harness all together, or keep it stock.

For the S2000, I recommend a 6 point, although it's use will be the same as a 5 point. Reason being that there is a frame rail under the centerline of the seat that will prevent you from mounting a sub strap centered under the seat. I use a 6 point with the sub straps mounted on each side of the frame rail to deal with this. I don't think you can properly mount a single sub-strap (5-point) without getting very creative.

For mounting locations: mount the shoulder belts to the harness bar on your rollbar (don't use a harness if you don't have a rollbar). Mount the left lap belt using an eye bolt through the same hole that your stock belt mounts through (the thread pitch on a Sparco eye bolt is the same as the stock seat belt mount bolt here). Mount the right lap belt using a proper backing plate at the transmission tunnel and low down. Use as big a washer as you can on the inside of the car. Be careful positioning here because you might find (as I did on my first attempt) that the metal piece for your belt length adjuster thingy will wind up in a weird position where it doesn't quite make it into the seat area, but shouldn't really be sitting outside the seat. Mount the sub straps on either side of the frame rail about as close together as your backing plates will let you put them. Again, this will not have the effect of a true 6-point, it will work like a 5-point.

Pictures of my seat/harness setup

webdiva

I have that one...the Schroth (in pink!) but I haven't put it in cuz there's no place to mount it and Tony (PayneInThe) advised me that I'd need a roll bar with it. What about the CG Lock...am I ok using that (for Autocross)?

Tony...did I miss you out at the race on Sunday? You missed me beating the hell out of Wing's Evo (my S was in the shop. Toasted clutch) ! I also got to drive an STI on Saturday!

payneinthe

CG Lock is fine because it doesn't affect the upper body restraints. I did not attend the race --- it was my 7-year anniversary.

webdiva

Congrats on the anniversary! You have to bring the wife out, we'll get her in a Vixen Racing tank top soon enough!

slick

Thanks to everyone for all your comments and advice - very helpful!!