The Willwood brakes are getting fitted today. The fine print states if the brakes feel 'spongey' after the upgrade, and larger capacity master cylinder may be required (something to do with the change in bias flow to the rears and volumetric capacity?). The recommendation is upgrading from the 2 bolt master cylinder and brake booster in the GQ to the 4 bolt master cylinder and booster out of the 4.8. ( Brunswick don't change the brake booster or master cylinder when they do the upgrade.)

Has anyone done this upgrade, is it a straight swap? Is the 4.8 unit physically larger in size? Where can i source a service kit for the booster as the units are only avail s/h from P.A.P.

The kit includes braided lines as well, however these are already fitted.