Ah, so you're looking to build a bit of a sleeper are you Ruffus you old rogue! Should be fun at the traffic light GP.
@Neil, I could not resist when I saw an inexpensive MSR performance muffler. (pls see pics)
Had to be restuffed and refurbished a little bit, but fits nicely and sounds even better. No speed increase measurable.
Even filled with stainless steel wool from kitchen scratchies (14 pc) has this muffler 1/3 of the OE s weight.
The catalizer (uncontrolled metal oxydation cat) I removed because of extraordinary heat built-up (pls see pic db-killer) within the pipe and blueing its connection tube.
At this rear db-killer I experimented to find the proper sound by closing airholes with riviets.
None of them stayed (melted and were blewn away) in place thanks to enormous heat, caused from catalyzer. Must habe been around 500°C to destroy this aluminium reviets.
DB-killer front and rear are mounted to avoid too much of noise.