[mikedsilva]

Something I have realised through some experiements, is that quality mufflers tend to actually reduce db... I've used a few cheap ones and some have sounded like they did nothing, others have blown out the packing...

The Vibrant Ultra Quiet Resonator looks like a small muffler. It works. I think that two of those, running separate paths (not crossed or merged) would work well and reduce noise a lot.

If I had a lot more money, time and welding skill, I'd try them all out.