Hey guys decided to join the club. I have been very happy with my K-cars but the Z-car has so many interesting inovations and what sealed the deal was the awsome sale price. I have been working on it on and off for the last few days, as you guys noted great build quality and no issues so far. I have a RC-Monster motor mount on order but one thing I didn't like was the limited pinion options due too the motor can hitting the chassis brace, as MetalMan mentioned. A 16T pinion will barely fit, and that gearing was too high for track I run at. I thought about using a different diff with a 46T spur but I found out the Z-Car diff is actually much smaller than normal, sort of like the new Kyosho MP9, so for now you can only use the Z-Car diff and 44T spur. I always felt that if a car was designed to be electric from the begining (and not converted from nitro) the chassis brace would be on the other side, so I took a few measurements and decided to move the brace to the other side. I had a few braces laying around and I found one that fit perfectly. It came off a Kyosho 777 (rear brace) and all I had to do was cut a small notch in the Z-cars rear brace mount, swap the brace to the other side, make a small aluminum spacer that is threaded, then just screw in a few bolts and anchor the brace to the chassis using one of the nitro motor mount holes. The chassis feels the same (flex wise) as it did before. Won't be able to test for a while, but I figure the part I modded only cost a few bucks. Kyosho also makes a really cool blue heavy duty brace (WC 777) which I may go to if this one works out ok. With the braced moved over You can go down to a 11T pinion if you want. you now have a lot more gearing options.
Here is the spacer I made to take the place of the stock Z-Car brace. Bolts screw into to both sides for strength.
I have the motor sitting in the car with a 12T pinion, you can see there is more room for probably a 11T if you need it.