Yes I think the diff spring kits work well and I run it in mine. I do not even want to think how much I have in mine as it has had many different faces. When I first built mine I had a lot of alloy on it till I found out the hard way all the problems with alloy. Then I up dated it from a MT 1 Racer, which was a kit that came with out a radio system or engine to all most MT2 SS specifications other then the upper deck and radio tray. I just recently took the OS .15 CV-RX out and buy an OS .18 TZ in. How much do I have in it WAY TO MUCH! But I do think I have gotten my money out of it and I am still driving it.