Std rail pressure is 3.5 bar with vac pipe off and plugged.
As said most chips are written for the std rail pressure, injectors to use is really down to how much you want to spend/how easy you can get what you want, power you want.
The good old 403's,(greys) will go up to around 450bhp@ 3.5 bar on a yb engine, and IF mapped correctly will give excellent results, mine was 0.97% CO, and 137PPM on last MOT, could crack 40mpg also, despite 200K miles on std original bottom end, BUT they are no longer made, so if any problems you might be stuck if one went duff.
Probably better to use siemens or similar current(made) injector just in case.
I would do all your mods at once then get it mapped after fitting all the bits you want.
A .63 exhaust housing will be very laggy compared with a .48, but has more potential before running out of steam, and will come in with a harder kick, which you may or may not like, I tow things like cars and a caravan, so need something less laggy.
tabetha