RE: MPI clutch springs
as long as it'll fit tight around the clutch shoes, you'll be fine. I haven't actually seen one of these springs in person in a while (or a t-maxx clutch) but IIRC the Maxx clutch setup is quite a bit smaller than ours, so if the spring is longer than the stocker, it should even be easier to fit around the clutch (I have noticed that the stocker is a bit small for the clutch shoes)