I have had my eye on the Tamiya Silvia Coppermix drift kit before I got back into R/c.
Recently it disappeared from the store I always saw it on and it looks like you can now only import the model from America or Hong Kong.
So I decided to instead go for a standard chassis XB RTR version of the model and upgrade it myself as these are cheaper and more easily available.
It arrived today from Germany and has already had its first upgrades installed.

The initial hop ups I have installed are an aluminum drive shaft and race bearings to replace all standard bearings / bushings.

I found the main gear can be annoying to get back in without taking the rear differential apart. When you take the drive shaft out the bevel pinion gears attaching to the diffs drop making it difficult to re-insert the drive shaft. Good job I had to replace the bearings in the differentials anyway.
All in all its pretty easy to take apart and rebuild.
I have drift tyres and a sport tuned motor on the way as the next step.