In case it could help, Muzzy is selling a quiet core (±$65) to mute down a bit the muffler's tone. It probably will still be kind of loud but maybe it will fulfill your need?? It is not mentionned on their website so you must write or call them.
Also, you could try to find an OEM exhaust from a ZZ-R1200. It have two factory slip-ons that give you the choice to get after-market ones and alternate depending on how you feel.
I will check with my parts guy at the dealership tomorrow 8/28, I seem to recall that he had/has a stock ZX-11 D exhaust laying around that he would like to get rid of. I am going to be putting a stock ZZR1200 exhaust on my ZX-11 this week sometime and I will have a Muzzy for sale. It was on the bike when I bought it and I am tired of it. I will eventually be in the market for a set of Staintune mufflers for a ZZR1200. A little noise is OK. The Mussy is also a high RPM/HP pipe. It does absolutely nothing for the mid range mich is where I think most of ride most of the time. I know I do. I'll let all know about the stock ZX-11 Exhaust. Jay
I had this exhaust put on @ the dealer when i bought the bike, and never had the stock setup. 47,000 miles
its really not the noise level. i just hate the way it sounds under 3k . Since I've gotten older and rarely see more than 6k. its time to change.