ignition curves and performance

Clearly I have an addiction. Two actually. One is working on my bike and the second is riding it. I'm just about out of mods to do, short of boring out the engine to 615cc (from 550). One thing I haven't messed with is the ignition. I found this ignition kit on Webike, which has selectable ignition curves (all custom configured for the zr400/550), as well as a rev limiter, a hotter spark (which allows for a larger spark plug gap) and rave reviews translated from Japanese (e.g. "torque is overflowing"). It's pricey but if I can manage to eke out a little more performance I'd be happy. Has anybody had good/bad/indifferent experiences with adjusting the ignition timing on their z?

japan.webike.net/products/21586552.html

I have noticed a little more zing with plug gaps that were much wider than stock... like 50% wider or more. But that really stresses the coils. Eventually I started to get misfire at wider throttle openings due to sparks leaking out along the plug wires or out from under the plug boots. Eventually it will wreck a coil.

I would imagine the ZR ignition is probably pretty good if it is like the Zx550 curve. I haven't played around too much with timing other than total advance. But I already start to get a little knocking on hot days in the summer if I don't downshift and give it too much throttle. This is with the all/nothing mechanical advance, though. I think the Zx system was good upgrade for a Kz, but they are getting harder to find nowadays.