The following might be wildly inaccurate, but here goes:
1996: Downtube routing for both front and rear mechs. No seat collar thing for cantis. Back to two brake cable stops on top tube (like the 1993 canti model) but no canti hanger welded on rear stays, as it used a V-brake.
1997: Downtube routing for rear mech only. Double top tube routing for front mech and rear brake.
96 Hei Hei, came with Maguras. The canti clamp was still available if you wanted to run different brakes though and it should be remembered that Vs didn't apear until later in 96 after the Kona model year setup was defined - they appear first of 97 model year bikes which became available in late 96. Mid way through the 97 model year cable routing for the rear deraileur changed to the top tube on both the Hei Hei and King Kahuna.
numbering system also changed slightly for the 98 model year to KK..... for King Kahuna and KH..... for the Hei Hei. Prior to 98 its B for Hei Hei and K for King Kahuna.
Given the frame number I'd say its a later one (96) as 20" frames weren't that popular, and it is number 538 in size 20. The seat tube it stubbier on the 20" frames too.
Now hurry up and post some picturs and I'll go through all my photos, catalogues and tech info to pin the year down.