If the car is "only" a basher and you don't have to be d'accord with some racing rules maybe the 17.5 turn combo is getting boring quickly unless you don't optimize final drive ratio things. Without 2nd souce gadgets you cannot achieve lower FDR than 5.74, which is not really that fast...
To get some decent speed from a 17.5, you have to get FDR of 4.0 or even lower. To do so, the Yeah Racing motor mount ist needed, this Item has no fixed motor mounting points like the Tamiya part and allows you, in combination with 64dp gears, to get nice gearing for a 17.5 rocket.
You can Check "thercracer.com" for more information about proper TT-02 gearing and additional tons of TT-02 related articles, Tricks and such stuff.
My son (6 years old) is running a 21.5T Hobbywing and SkyRc Toro TS50 ESC Combo on 2S LiPo with his TT-02, FDR is 3.9
This works great for the young man and he has loads of fun to race the local supermarket parking lots!