These are the three options I know...
BSQ subframe reinforcement kit (
http://www.geocities.com/bretq/mounting_kit.html)
BEAKS subframe reinforcement kit (
http://www.beaksproducts.com)
COMPTECH tie-bar/subframe reinforcement (
http://www.comptechusa.com)
BSQ - $20-25
BEAKS - $65
COMPTECH -
$190 on eBay, seller aofeparts
Personally, I have the BEAKS kit, but I am considering changing to the COMPTECH piece. Since I have already installed the BEAKS kit (which means removing a tack welded nut) I will probably have to continuie using the back half of the BEAKS kit.
JD