Review on Kawasaki Ninja 400 Z400 Slip-On Exhaust System Including Muffler For Improved Performance - Compatible With Models From 2018, 2019, And 2020 by Michael Duman

I just installed it so can’t comment on long term quality, but initial impression is great. As everyone else says, the midpipe is a tight fit over the stock header pipe. It definitely could have been forced on, but rather than beat it on I used a small tail pipe expander to widen the end of the midpipe just a tiny bit so it slid right on without forcing it. Other than that the fit and finish looks great and everything lined right up. I tested it both with and without the baffle installed. It sounds great either way, but I’m running it with the baffle installed just for personal preference of liking it just a little quieter.