Some questions on converting my savage

[doo540]

I have a XL with a Kershaw Design's motor mount. I run a MMM V2 with a MaxAmps 4S 35C 8400 lipo. It fits under the motor inside the frame. Motor is Neu 1515 1Y, 16 tooth pinion, stock spur, radar confirmed 48 mph. I find its very controllable at that speed for bashing and makes for huge air when jumping. I'm still running the stock 3 speed with no issues. I'm currently doing the CEN GEN diff upgrade, I blew thru 3 stock savage diff pinions. THe truck is otherwise mostly stock, except the tires are Losi Bolt-On with Proline 23 hex rims. Hope that helps.