The Gold head is the 3 port legal version where the silver head is the outlaw version.
The silver head has 2 versions the 138 3 port with modified crank and the 168 5 port version
Th gold head has 3 ports with non modified crank.
I have used the 3 port silver head version for some time and it takes ages to break in. I found it to be at its best after 1 1/2 galls of 25%!!!
Check the head clearance. It comes with too many shims in. I took them ALL out to get it to work properly
Dedicated RC Car Speed Site
Norfolk and Chance