From reading many threads, and for ease of tuning, if you do change injector sizes or add additional injectors, it\'s best to keep the primaries as 550cc. That way you only have to worry about tuning past 3800 rpm when the secondaries kick in. Ideally you need some way of tuning injectors - so replacement ECU, piggy back or fuel computer in preferred order (based on how may factors are fed into the fuelling maps).
I went with a hybrid turbo - bigger front end and ported stock back end, which is good for well over a bar with correct fuelling / cooling - and you will have to do both !!
Stock intercooler loses it\'s way rapidly after about 10 psi (0.7 Bar).
The other thing to consider is that if your pushing a lot more air / fuel in then timing needs to be retarded as well, otherwise the engine may suffer.
There is no substitute for a lot of reading up - both on here and other rotary forums.