I changed from the ND21 model to the ND23 model, and the muffler noise became quieter, so I considered replacing the muffler, but I was also interested in changing the intake, and I liked the design that allows you to replace it discreetly, so I replaced it. (You can't see the red color unless you look closely, as in the photo.)

I don't think the muffler sound has changed noticeably, but when I'm driving the intake sound has changed and I now feel like driving with the windows down even if I don't have the windows open.
The response also seems good, so now I want to try installing an intake suction kit.

●TOMTOM from Saitama Prefecture (Roadster/ND)