My car has done a few runs in standard trim, and I'm now in the process of getting a few key hop-ups before it's first serious race meeting in May.
So far the car has been great, handling well, very quick acceleration, nice smooth diffs etc.
But you have to face facts, whilst the design is IMO better than any other 4wd on the market - it is still a "basic" kit - one that does require a few hop-ups to have a serious race-ready machine.
either Tamiya's DF02 alloy shocks or their new DF03 shocks soon to be released. Losi and AE shocks would be good too - but you will have to fiddle around with body and shaft sizes to get them to fit well in the front.
Normally, the stock dogbones are quite ok on a normal Tamiya car, however in an ironic twist, this car so much suspension travel that the dogbones are sometimes coming out. Tamiya's DF02 CVD's fit perfectly.
Tamiya's slipper will be released soon, however it seems that it will only accept their own 0.5 module spurs( like the std kit). Realistically, you would only need a handful of pinions to have a suitable gear range but some people will definately want to run 48dp.
A gear adaptor is available from one of the Tamiya Club members (Gary), I have one, and it's very good, plus there is likely to be more options available soon from 3racing, Kose, Tobee, Square etc
That's all the car really NEEDS. Turnbuckles and possibly better ballcups could be useful too, and I'm sure Tamiya have other options soon to be available like a motor plate with additional heatsinks, roll-bars, one-way etc
By my calculations, it is concievable to add everything I've mentioned above, and still come out with more money to spare than if you'd bought and X5, BJ4x4, Yokomo etc