This aluminum main shaft is an essential hop-up when you have a motor <27T.
It reduces the friction, is a lot sronger than the standard plastic one and it also looks nice. But that's not everything it also accelerates better and brakes a lot harder. It's not essential to get aluminum cup joints, works good without. Andrew Seccombe said that it is slightly too long, but i didn't experienced that, it fits perfectly in my TT-01E. I will not hesitate buying it, it is well worth the money.