So you have an Astra and Vectra now or are you just doing the Astra with a view to do the Vectra?
The nozzles upgrade question you started with on AON, I have had injectors made up by United Diesel as Harvey did and had the flow propperly tested. The results were 10-15% increase at most, which is not enough to make a big difference and why Harvey smoked so heavily to make decent figures.
United Diesel are going to take a set of injectors from me this week and do some development work with flow and nozzles to hopefully get at least 30% (they said 50% but they were expecting 20-25% more from the last upgrade). The injectors they did are running fine though in a Saab 93 TDI at the moment and with a hybrid and water methanol system to help the spool, it is making better results.
You might want to look at a water fumigation system to aid in the spool of that 2260. Without my water/meth kit I am hitting peak boost of 30psi at about 2800rpm in fourth. This my kit running I can hit peak in fourth at 2400rpm and in 5th gear I can hit peak by 2250rpm. In sixth gear the VNT duty is too high for the amount of flow in the exhaust and it actually chokes and stagnates, peeking later.