Stock boost is 0.8bar off the top of my head, if you have a CAT back exhaust you could easily see 0.9bar. Other modifications like FCD won't increase the boost pressure, only a free'er flowing exhaust, a Decat or a Boost Controller would. My car has the first CAT removed and it hits 0.9bar. To check for yourself, jack the car up and have a look underneath to see if the CATS are still there, if you hav an aftermarket exhaust, odds are one of them will be gone. If both are gone and your hitting 0.9bar then I would say you have a RR installed, but typically you'd expect 1bar+ if that was the case. What gear do you have it in when you read the 0.9bar? Does you Boost Guage have a peek hold function?
To check for the colder grade plugs, remove one and post up what it brand it is And to check for a FCD, do above and check inside the passenger side footwell under the carpet, it'll only take 5 minutes. Checking the fuel pump will take a little more time but it's not too difficult, have a look in the FAQ's section and check out how to install a fuel pump for BPU