I was thinking about this too but i would like to ask about improving the flow even more. What if you cut a piece of pipe out at the Red arrow section? Or even at the Teal arrow section and have the exhaust just escape freely from there? Would the sound be too loud for street use?
This is what i'm talking about. If you cut the yellow parts out with a power saw or if u can get the muffler off you could probably use a hacksaw. The exhaust would go in and fill 1 chamber and get right out of your exhaust tip bypassing all the chambers. You could also probably fashion a straight pipe from that entrance to the exit. I think you would also have to block off the teal side of the muffler with something maybe weld a piece of metal, or some kind of metal clamp with a cap. I guess it wouldn't hurt your exhaust system if you left it open too because it would just recirculate to the first chamber.