Thunder Tiger Avanti
I have one and all I have done is to replace the nylon prop with a metal one thus there is very little increase in performance and the reason for doing this was due to the nylon prop throwing a blade after striking an underwater object.
Prestwich Model Boats have a suitable replacement motor complete with a better ESC than the existing Ace one and their system can handle up to 4S Lipos instead of the stock set up of 3s .
I have located a source of a 4S Lipo which length and width is same as my 3S one but the height is a little more and it will fit into the battery box. To trim it out properly I would have to add some ballast to the starboard side. Due to the electrics including the battery all being in a small watertight box at the stern there is not a great amount of scope for a lot of mods.
Boaty😁