Have a look at Christian Majors thread in the resto's room. He's got the best S2 strut brace I've seen.
Just a shame about the monkey that welded the brackets on for me.
I'm no welder, but I know I could have (and infact did do) better than that myself, but for some reason he thought it needed re-welding.
A decent Strut brace on an S2 isn't easy, getting it to clear the Inlet AND the heater box is tricky. The Sparco/OMP ones don't seem to sit on the turrets very nicely either, but they do work OK. I would certainly drill 8mm holes in the turrets and nut/bolt it, at least then you can pull it down nice and tight.