I am interested in this thread , as I have acquired a Tamiya KT ,second hand. I have put in springs replacing the tamiya ones and it seems to have improved the tamiya system. I am however looking closely at the Schumo and Darryl turner systems ( just in case) I will get the geardown system as shown in the photo, tho the proportional speed on the KT is pretty good.( Tanks should be able to just crawl along)