I am running the SSD 2 speed with a MMP/Tekin Pro4 3300kv combination. The pinion is a 14 tooth with a Robinson 64 tooth slipper, and I am using the 13/43 underdrive diff gears front and rear. The 14 tooth still allows for a very low speed easily controlled crawl, really low speed at that. Initially I was using an 11 tooth pinion but it would wind out quick, even in second gear. The 14 tooth will really run in high gear, but as I said it will slow down to.... well a crawl in low. I am extremely happy that I put it in, so far it has been a lot of fun and at least in my opinion has added to the capability of the Bomber. I am very happy with it!