My friends one which was screwed on we managed to get nuts and bolts but you have to remove the shocks to do it and then it made it very tight to get the 19mm socket onto the top to tighten the shock.

Here is a picture of the strut brace fitted to the rs turbo before we took it apart for a restoration:-



Tho this one on my friends saphire is much easier to fit, i dont know if you can get one like this design for a erst. You can see the back bits on the turrets the strut brace mounts too but it isnt attached in this picture.