dont think they make much or any difference at all, something like soild top mounts would be better to tighten up the front and be more effective than a strut brace.
Rear ones just bolt onto the damper tops in the boot, he front ones require you to drill the arch/strut (i dunno the best word for it)
http://cgi.ebay.co.uk/OMP-FRONT-REA...ryZ40192QQssPageNameZWDVWQQrdZ1QQcmdZViewItem