Are these used for NA application or turbo ?
In NA application can I expect any engine performance gains ?
2) Yes and no. It's not a straightforward answer. This is one of those 'if you have to ask, you shouldn't be trying it' things.
They said they can do "pretty much anything" to compression ratio. The pistons themselves will be heavier than stock, meaning if you copied the stock compression ratio (and essentially nothing changed), then you would have an ever so slight loss in performance from adding on rotational mass...
That's going to be the most drastic difference between stock and aftermarket. Pretty much looking at AT MOST 350-370bhp running stupid high compression ratios that would need a lot of support to manage over any amount of time.
Forced induction applications benefit from reducing compression ratio. The forced air charge makes up for it, when calculated correctly.