Depends on what mods you have and what boost you intend to run.
im going to turn my boost up to 15 psi on a ct9 today.
i set mine at 2.7 bar untill it got to tuner, u dont really need to rolling road it unless your mapping a uprated ecu, all my tuner done was set a wideband onit set the boost to what i wanted then adjusted the fueling correctly, oviously wen u add more mods then rr is best option.
what difference will it make if i set the pressure with the vacuum pipe on or off?
most tuners iv spoke to say 2-2.5 bar above boost pressure
Does anyone actually know what the stanard AFR roughly is on WOT? You're aiming to keep this or less to keep temeratures down.
The simple solution is to run enough fuel pressure to ensure that on WOT a safe AFR is reached. This downside is running needlessly rich through in most other scenarios, it's crude but you certainly don't need a rolling road!
Buy a wideband and set it up yourself, I would suggest you're aiming for around 11:1. Other people will have a better idea of what this value should be.