DB-01 Parts Question

[MITamiya]

Hello Everyone,
I am about to start a DB-01 build and I have a couple questions regarding a parts selection.
1) Can someone tell me the difference between the WO universal shafts (54118 & 54119) and the regular universal shafts (54015 & 54016). I'm not sure which ones to get.
2) Can someone also give me information with regards to which chassis is best, the carbon reinforced (54041), the high traction (54204), or the standard kit chassis. I am sure it has to do with flex, but any further information would be appreciated.
Thanks!