Okay so i have sparco seats in my r53 and want harnesses but i need to keep my back seat.
Is there something i can mount behind the seats like in the trunk so i can lay the seats down and use the harnesses.
Or some other ways?

 

Is there a reason that the Schroth or Schroth Pro, won't work for you? Or were you just not aware of them?

 

The Schroth Quick Fit system is what BlwnAway was referring to, works great in my '05 MCS, and they come out quick and easy as well for daily driving.

 

Here's a possible solution!

http://new.minimania.com/part/NMC104...-Mini-Cooper-S

The Cooper bar is stiffer, stronger & lighter than any other bar. The Side Plates are made from CNC aluminum and allows use of the stock belts or any other racing belt with a wrap around loop. The bar is easy to install and removes in minutes. It's made of aerospace aluminum and weighs less than 6 pounds. In addition, the bar stiffens the chassis and does not occupy or require rear seat removal.

The Mini Cooper Bar Retains stock seat belt attachments with adjustable height feature. Only minor trimming of plastic B pillar covers. 100% bolt-in easy installation.

This Harness Bar was designed and analyzed (NASTRAN) for not only compression buckling but out of plane bending due to beam bending under load. The design load is 6000 lbs and it has large safety margins based on yield (i.e. elastic limit).

Unlike some of the other harness braces on the market, this harness bar does not rely on the headrest posts to keep the harness centered.
Mounts between the B-pillars.

Drive Hard. Drive Safe. Keep Grinning.

 

IMHO, If you're not going to install a true roll bar/cage, then the Schroth Quick-Fit Pro (HANS compatible) is all you'll need. A harness bar may offer additional chassis stiffness but unless you're Lewis Hamilton, you won't feel it. A harness bar will not offer any additional safety in a roll-over and for the price, you can buy two Quick-Fit Pros and have money left over.

 

Which Sparcos do you have? Depending on what you have chances are you are going to need to do a harness bar at the minimum and harnesses. The high bolstered sides will keep you from ever being able to get a quickfit to properly tighten down around your lap.

Unfortunately you now have race seats in a daily driver and need to decide which of the two you want to keep most, I would highly recommend either removing the seats and going with the stock seats and quick fits or doing it right with a proper harness bar, seats, and harness.