Yeah sorry I am trying to pick paint at the moment - the R34's came in a few different silvers (see here). Kinda looks like sparkling silver to me - it would have the paint code in the engine bay on the plate with the vin / engine no etc.
I personally wouldn't push the ceramic turbos over 12psi but thats me. Many have ran them at around 14psi reliably but then again others have not - and when they shatter they can take the engine with them. I would prefer to spend $3k up front on some steel wheel turbos for insurance, rather than $15k on an engine + turbos after disaster.
I am not sure how the R34's are tuned from factory, but the difference going to power FC on my R32 was unbelievable. It netted probably an extra 20rwkw just from trimming the fuel. The stock R32 ECU had the AFR's at around 10:1 - very rich. After the change fuel consumption around town also dropped dramatically - like from 250km per tank to 350-450km.
At a guess stock standard + well tuned power fc, and boost at 12psi I would think peak around 200rwkw. Add some steel turbos @ 16/17psi, maybe a nismo fuel pump for insurance and a decent exhaust and you will start getting up to the 300rwkw mark.