Race Harness.
 

I'm thinking of mounting a harness for use in the occasional track day as i do move in the cabin a lot with the stock seat belt.

Mounting points would be the 2 in the rear seat (the child ones afaik) and the bolts that hold the stock seatbelt on either side of the drivers seat.

Am i missing anything here?

I'm not an expert in mounting harnesses, but I wouldn't mount belts to the hooks for the child seats, I think they're really only rated up to 65 lbs or so. When you take the seats off and see them, you'll see how thin they are. Normally you would install a harness bar, or have the belts mounted to the rear seat belt holes.

My recommendation is to invest in a harness bar. It's pretty straightforward to install, not hard to remove, and will look better. Most importantly it's designed for these stresses.

Not to sound like a **** here, but don't get a harness unless you need one. Just my 2 cents. The stock seats are still very supportive even with only the stock seatbelt. Unless you're sliding out of your seat, there really isn't much of a point in upgrading to a harness. Again, just my advice. In the end do what you want :)

I'm a bit of a big guy so i do slide out in hard corners, I'm doing my first track day this weekend so ill see how bad it is on a track.

Alright harness bar sounds like the way to go i guess.

Get in the car, snug yourself as tight inside the seat as possible, maybe even recline the seat back a slight bit, or back the seat 1 or 2 notches. After this, grab the seat belt and get it really tight up on your shoulders and then give it a quick pull and lock it. It should be pretty tight, but moving the seat forwards again and/or lifting the seat back will get the looseness out of it. You`re now pretty locked in the seat. There will be a bit of movement, but having the seat belt locked should let your arms relax under braking and still hold you pretty good in turns too.

Do *not* get a harness without a harness bar. The harnesses are specifically designed to operate at a 90 degree angle, so the belt needs to go straight back from the seat. Additionally, I'd stay away from 4 point harnesses- they struggle in protecting against submarining, which can kill very easily.

Generally I've heard this advise:
1) Stay completely stock, with airbags, belts, seats, everything
2) Go full on safety aftermarket- wheel, seat, 5 or 6 point harness, harness bar/rollcage.

The "in between" setups are usually the most dangerous of all, and most of the deaths that I've seen come from those poorly done halfway implementations.

The stock setup is extremely safe and good. Don't mess with it, unless you are actually going to improve it all the way.

I agree as this is what I've heard from racing outfits as well. On a track, do it right or don't do it at all.

That being said, I do plan to run a Schroth 4 point anchored to the rear belt receivers for autocross while retaining my factory belts for all other driving. It gives a lot of the benefit with less of the hassle than a full safety rig, and for driving around some cones in an empty parking lot: I'm not too worried about flipping the car.

Different means to the same end, he could buy a CG-Lock.

I do they poor mans CG lock, twist seatbelt at the buckle.
The child restraint are NOT strong enough, it's expressly stated in Scroths documentation. If I were buying & putting one in I'd get the Scroths. One of few (only?) approved for street use. One shoulder strap is designed to give in a hard impact so it'll act more like the standard three point and reduce chance of submarining. Shoulder straps will probably be attaching at the lower rear seatbelt points, I'm pretty sure the FRS seats are strong enough for this, the seats I recall are approved for certain race sanctioning. The rear seats are kind of close though so the angle might start getting too steep for safety. I actually haven't checked, has Scroths listed the FRS/BRZ yet?

Dont get a harness bar, those things are a fake. Iv seen harness bars bend when people get into rear and side crashes causing slack and making the person slam into the steering wheel (responded to a few calls and seen them in person.) I would either buy a roll cage or a full cage, but I would never buy a plain old harness bar. Or you can buy a roll cage and a harness bar if the roll cage doesn't have a place to hold the harness straps. Also spend the extra money on a 5 point harness, with a 4 point you can slip under the harness.
Here are 2 great roll cages with harness bar setup
http://battleversion.com/store/fr-s-12/
http://www.frsport.com/Cusco-D1-Roll...Z_p_32841.html

I would buy something like this
http://www.ogracing.com/blog/wp-cont...rness-bar3.jpg

Avoid something like this
http://www.corsportusa.com/store/cat...lled_1.JPG.jpg

Harness bars are evil. People keep saying different things but the only things I know for sure is that a full set of safety gear gets the most votes and stock gets tons of safety testing.

Look at the Schroth 3 point systems. For autocross and occasional track day they are very good.

who ever said a harness bar is a roll cage? there are many roll cages that have a straight bar right behind the seats for a racing harness setup. You either go all out on safety or you dont do it at all, safety is the most important thing.