the RCS products for the ZDZengines are JMB silencers .
these are NOT tuned cans or tuned pipes -
they do quiet things very well (best of any muffler/pipe etc., I have seen or heard) and with proper selection (ask ) , they don't hurt power and also install in a much shorter space arrangement -
Do use the largest size allowable from each selection -
We have run -and have used every size listed -
My 210 setup -actually runs a bit faster on the biggest mufflers -than on open exhaust.