It was feeling nice.
Unfortunately the stock (see ceramic turbines) front turbo decided to let go at 5psi and I now have 25psi compression on 1,2,3. This is appearing more common than I initially thought possible, but when the ceramic turbine let go on this setup (RB26 style) it is often ingested back into the 3 cylinders and scores the bores and stops the valves closing.
I would never do this again with the stock GTR turbos as they tend to be more prone to failure after being removed. That said, it would be too expensive to bugger with using expensive turbos. I think I will be dropping in a complete RB26 for a number of reasons, although they aren't as punchy low in the rev range.