ORIGINAL: magnat
Yes the D has adjustable settings and the stock one Doesnt
While the D is Nice, It is Not 100% Essential..
You can Hop up a TT-01 to a TT-01 D if Your really like, it just depends on Your finances at the time as to whether you get the TT-01 or the TT-01D
Personally if you are debating between a TT01 or the TT01-D and finance is a bit of a problem at the present moment I would personally wait the week or the month to be able to buy the TT01D as that it comes with certain hop-ups that are necessary like for example the ball bearings. That alone is priced more than the price difference between the two kits and with the TT01D you receive many more hop-ups which have been discussed within many threads in the drifting threads and also the TT01 thread.