on my buggy I have used both chassis (flex&non) my truggy I have used only reg roller chassis ... unusual that the tuned chassis is more reasonable ... I would go with that(tuned being cheaper)although personally I prefer the stiffer ride with regular race roller chassis ... I have had bad luck with aftermarket towers (not losi) although khz aluminum is the only aftermrkt aluminum I will use other than losi so if its reasonable enouph go for it ... 3racing and integy towers are very soft compared to losi aluminum ... khz seems to be a bit more crisp (hopefully not to crisp ,SNAP&that can happen) ... some of the top racers I have been around say if it dont say losi on it dont use it ... although I do fiddle around with some other brands if I find good deals and I have a little extra cash ...