Well I searched for info on fitting the early airbox on the KZ900, a few things came up but apart from one post by wired George who said yep, it fits, not a lot of info, some "thought" you "might" have to cut up your side covers but nothing concrete that inspired me to go ahead and buy the airbox, I bought it anyway hoping it would go on, I was gonna get it on somehow.
So it arrived this morning and I now have it on n thought a tip or two might help or inspire others to piss the pods off n put the early airbox on.
It goes on pretty easy, I just loosened the carb clamps, left the cables attached and dropped the carbs down, I put a towel each side under the carbs so as not to scratch my new engine paint. Then I slid the carb rack out the right side so #1 carb lined up with #4 intake, give or take, the rack stayed there with no thought of it dropping down or out.
So then I worked the airbox in from the left, you need to bend the intakes and work it in, the odd cable tie on the frame rail had to be cut off for max room.
I didn't need to use the old airbox support as the box sits on the cross member that holds the battery box in.
Now with the box roughly in place I put the carbs back on, from there you just have to work the hoses onto the carbs, don't forget the clamps, I found it best to fit and clamp #s 1 n 4 first, this made it easier to put the inner two on and clamp as there was a bit of pressure now with 1n4 now on.
It fits like a glove and there is no need to touch the side covers.
Hope this helps someone else who's frustrated over the scarcity of the stock KZ box, sounds like they're a pig to fit anyhoo, goodbye induction noise.