This may be way off base, but is my only experience with modifying stock mufflers!
Before I turned 16 I had a Go-ped, a scooter powered by a 25cc 2-stroke weed-eater engine. Of course I began to modify it, and the first thing to go was the "floss" insulation that was in the tin-can muffler (made the scooter louder and supposedly added some sort of performance...who-knows)
Obviously the differences in application might be more than the similarities, but that insulation definately decreased the volume, and raspiness!
I'm really glad you're willing to begin some experiments. My scientific mind says, change one thing at a time so we can determine exactly what needs to be done, no more no less.
I would remove some insulation, leave the existing perforations and see what you get. If indeed that is a cat, I suspect it would be best to make the left and right symetrical.
Originally Posted by Cbozz
First, make sure you'll take pictures of every step... I wanna see exactly how its done... If you can of course.
Second, I would replace perforated pipes but I would leave some holes in them so there is some muffled sound and its not a straight muffler delete and I would also leave cat as well... Also someone on here said that removing the wool material from inside the muffler box would help the sound.. I would try to reduce the amount of it in there..
I wonder when you are in the process of doing it you can somehow rig the muffler closed and temporarily put it back on your car so you can check the sound before you weld it all shut and put it back on....that would be the best to get the exact sound anybody's looking for...right