Everybody will need to get a new exhaust at some time so what alternatives are there?
To be honest, not many. I tried an AV10 Cobra exhaust on my green M40,
and again on the blue one with the larger engine. It didn't work!
Because it was designed for a latter 'reed valve' engine the effect was to make
pulling away sluggish. It was also a different angle on the header pipe so hung too low
under the bike, grounding out on low kerbs and tight turns
I have a pit bike system fitted to my blue M40, along with the big cylinder this seems
to work OK, although there's no play in the mounts this isn't a problem as the bike has no
variator meaning the engine stays in one position.
I know other owners have taken time doing 'cut and shut' mods on systems
which they have got to work, but as a simple bolt on upgrade this is not really an option.
In short, if it works OK stay with a standard system.