Originally posted by Manticore
2/. you need to use kyosho clutch pinion especially the 2nd pinion as the diameter for the mugen pinion (2nd gear) is smaller.
3/. file the main chassis engine mount hole a bit longer to the left to ensure maximum spur/pinion coverage. AMG has it without making mod on the main chassis. may be I am using option chassis.
Yep, it fits OK just a few notes. Like Manticore said the Mugen pinion 20-21-22 tooth 2nd gears actually are different in diameter by quite a bit whereas the Kyosho pinions gears are exactly the same size (or at least very close). You have to pay attention to gear mesh more.
Also I did not initally file the chassis holes to get the coverage, but what I did find that by not doing this my clutchbell was actually rubbing on the outside of the 2nd gear. So you actually do have to file the chassis about 1-2mm to make better clearance for the clutchbell - 2nd gear. It does not do any major damage to 2d gear it just wears a slight groove into it.
The Kyosho centax off the RR may be a better buy if the price is good as it presumably will fit with no mods, only has 3 flyweights for better response, and they are lightened.