Stiffy
My Harrison is set up with 16" rims and Hopper Stoppers twin pot big brake pack for Holden hubs.
I bought my car part built with this setup and she's not registered yet so can't
vouch for them as yet. Looking at their website they should be an effective upgrade from basic GMH though.
Check out
www.hoppers.com.au
Hopefully they'll be able to help you out.