i was recently driving behind a 323 that was pretty hopped up, he had a brace that looked like it was attaching to the top seatbelt bolt and than again somewhere on the bottom, with a brace in the middle connecting the two rods, basically an H shape on its side.

Has anyone ever seen anything like that before. I thought that this would probably be very stiff, and almost have the same stiffening effect as a cage(almost, but without the rollover protection). also, people could rpobably attach their 4 point harneses to it. just an idea, maybe when i hav money and free time(not likely) i will try it

 

I'm guessing this runs width-wise in the car... That would have very very very little effect on a coupe.. You could bolt harnesses to it, that's true, but it does zilch for stiffening.. It's complicated, I'd have to show you pictures of a car and then show you how adding bars affects chassis stiffness, but trust me when I say that adding bars where you describe would do little to stiffen the car.