I am skeptical about pushing xp2.
How about neopan 400?
I'm skeptical about pushing anything.
Be sure that you choose a developer that is phenidone based, and I'd suggest mixing it yourself. Split it into a and b, and cycle through a series of iterations of what they seem to call "stand development" around here. The term is new to me, but I've used the technique for years. It is possible to get a bit of boost in the shadows and still keep the highlights from going nuts. Of course it is limited, but getting something for nothing is alway limited. There's always a price.
That is, A, then B, then rinse. Return to A, then B, then rinse. etc. I've done this in several cycles. It works up to a point of diminishing returns; I suspect that 3 cycles is about all you are going to get usefully. There is a lot of information about how to split developers on APUG, so I won't describe it. I haven't seen any mention about repeating cycles, though. I don't think anyone believes me. It would be great to test.
Diafine is a great developer that does this already. You don't even have to build it yourself. It's built on phenidone, and it is used as a two bath. They claim enhanced speed, but I'm (as I say) always skeptical. Despite all claims, I haven't actually seen results that confirm them. If you use phenidone in a developer (it seems to be just about the only reducing agent that gives rated speed) be sure it dissolves. I mix in hot water. The directions for Diafine say to mix at 125ºF. I don't think it dissolves at 125. It mixes fine at a much higher temp, up around 180. Of course, try not to beat air into it. Hot developer with oxygen = oxidation.
The developer you use is at least as important as the film. Often more important. Most important is to get a good match of film and developer for your particular needs.