Some updated pictures of my Z-Car conversion. Added the MMM, rx box, battery tray and some Proline Revolver tires. Took it out for a test run and found that the stock springs are way too soft even with max preload, until I can get some stiffer springs I may replace the shocks with some Kyosho Big Bores.
Metaman, what's the situation on the stiff springs? HobbyPeople.net shows the stiff front springs on backorder.

Here is the buggy the Z-Car is competing agains't, my brushless Kyosho 777 sp2.

Side-by-side