interesting reading. the link earlier is also very true about many things.
just a note on the RC40 construction that some may not know. the rear silencer box is actually two part. with a resonator in the first part and the silencer part to the rear. you can hear this on a new silencer by tapping on it. you can also see a weld spot part way down where the two chambers are separated.
i first found this out some time back in the 90s when my RC40 was getting louder and there was fiberglass packing hanging out of the pipe tip.
oh and if you are interested this is actually available (but you may still end up in the same position as you are now) as i have had to make a new whole system to incorporate a CAT