When I did my 250/500 hybrid , I used FMF 450/500 system .
The front mount I used kx250 06 rubber insulator , they seem to be stronger then the kx500 ones.
Bolted direct to orignal kx250 01 mount .The gap from insulator to FMF pipe was joined by a bit of flat alumiun held by high tensile bolts,nylon nuts worked well so far. Had to dent pipe for clearence around coolant pipe on right hand side of cyclinder.
I have a spare clutch cover with a crack on face perfect candidate for clutch cover mod, I just wondering if a
kx250/ 450 cover comes close . does anyone knows?