Depends which seats exactly, and where you intend to mount the shoulder straps.
The shoulder straps should be fitted so they slope downward about 10-20 degrees from horizontal.
A lot of people mount the straps in the lower bolt holes on the rear bench. THIS is the real no no !! The angle of the straps will cause the belt to pull down on your spine in case the unthinkable happens.
The sport seats in many WRX's and STi's, with the holes for shoulder straps, are suited for 4 points.
The softer seats, found in some models will not work well with 4 points.
I welded in plates in the boot, to accomate the bolts for the straps.
http://img.photobucket.com/albums/v6...s/DSCN0830.jpg