i just put a MUZZY full system on my 2004. i recomend getting slips  or go to a full 4-1 system. i think MUZZY is not making new stuff for the 03-06 Z 1000.
That's good to know. I'll stow that away in my little peanut brain.not much HP to be had. you do save about 25 LBS getting rid of the stock mufflers. the stock head pipe is very light , maybe 4 LBS. keep the slips you already have and just have fun. my 2c. i have seen dyno charts showing 2 HP at 9,500 RPM big deal. i am talking about 03 - 06 Z 1000.