VZ800 2006 - charging problem

Hi all!

So I have issues with charging on my VZ800 2006. Mileage 62.000 km, battery is 18 months old, and tested to 85% original capacity (state good).

The problem is...
I found out a couple days ago that the rectifier is undercharging the battery at higher revs than idle. Basically, upon testing, I discovered that idle charging voltage is 13,5v, but upon reving the bike it drops to 11,0v.

So, the obvious thing was to replace the rectifier. I went for a brand new, aftermarket rectifier (for bikes up to 8000rpm, 200vac input, and 30amps).

Upon replacing the rectifier it all seemed good. Buuuut... NO.

Now, the bike is overcharging the battery upon revs higher than 5000rpm. Up to 5000rpm it stays rock solid 14,3v, only above 5000rpm it spikes to 18v!! The spike is real, the headlight also boosts intensity, and goes down when hitting lower than 5000rpm.

Few testing I made after discovering the spike:

I tested the grounding across the bike - seems OK

I tested the stator - resistances are whitin spec - 0.4ohms; I tested output voltage - across all 3 phases the measurings are exactly the same - 30vac while idling, and up to 190vac above 6500rpm. But they all match, across all 3 phases. So the stator is probably fine...

The question is:
Is there anything else I would need to check, that I missed?
Is the output voltage of the stator actually ok? Is it too high? 190vac seems a bit high...
Is the aftermarket rectifier bad? Should I get the original new one?

My money is on the rectifier... Again...

Thanks!