Horizons Unlimited - The HUBB - Exhaust Modification

In the original 1993 xt600 muffler the silencing system of pipes and walls is really complex. The exhaust pipe itself is about 4cm in diameter, and the pipes that make the air rotation system inside the muffler are about 3cm, and the endpiece itself is about 2cm in diameter...

Making the 2cm end pipe bigger makes the sounds bigger, even 2mm in diameter makes a difference in the sound, and in the power too. Making it bigger seems to give it a little bit more acceleration power. I tested this with holes of different size.

My muffler was so rusty I made some modifications to it after cleaning it from all outside rust.

I welded some patches to it. I cut the end part off, from the muffler about 1cm from the end. Then I made a round 1mm (or 1,5 cant remember) plate with a 30mm hole in it and welded it to the muffler end to replace the original end piece. Then I made another but 2mm smaller in diameter round plate and to it I made a 30mm hole and welded a 4cm long, about 2,5mm thick pipe to it. Also I made it so that the 2nd piece can be attached with 2 screws to the first piece which is welded to the muffler itself :P

The sound is fairly good, and because the end is flat, it makes "flapping(?)" sounds if you decrease throttle quickly. But the sound is more metallic than in the original.

It was too loud for my liking if I wanted to just cruise very slowly and enjoy.
But I managed to glue a round piece of muffling wool (or whatever is it called) inside it, with a hole for the exhaust gases of course. And made the 4cm long end pipe a little smaller in diameter by rolling somekind of thin asbest cardboard into a pipe and then hammered the tube inside the endpiece exhaust pipe. Good sound.