update 22.01.10
In last week I bought
1. a new Head from engine X20XER from Astra G OPC - it produce on stock 160 HP from 2.0 n/a engine
(only 3000 engines were made :-) )
2. intake manifold from Omega B X20xev ( 2.0 - 136 HP engine) much simpler than my stock mainfold and should give me few HP and Nm
3. tubular exhaust mainfold by Michael Motorsport 4-2-1
4. I'm still searching for new camshafts for this head- maybe Świątek sports camshafts ( + 15 HP / 20 Nm ) or Dbilas ( ?? / ?? )