Just got feedback from the Wossner piston guy, these heron upgrade pistons offer -10.6cc of capacity, which is almost identical to the std "jp code"pistons. This would offer me no benefit.
The reason I am looking for new pistons is that in my past experience working on v8's etc, dropping in forged lighter and higher compression pistons is a "super simple" way of getting more power and response. It really is simple and it always gets overlooked. It seems like pistons is the last thing people change in their motor after building it up and realising it is the same as before.
Anyway now I'll be looking at shaving the head down with cam and adjustable cam gear to compensate.
I'll keep an eye out for 1.8L and keep updated. Oh yeah Wossner guy also said can make custom pistons for $250 each when I asked about flattops.