Big Turbo choice to replace a big turbo

[mituc]

I already have about 83k kms/51k miles on my GTX3071R it it still serves me well and it's great fun.
However, I've used it with the factory catback for a little while and it's possible that because of the high back pressure it developed some shaft play. The wheels do not touch the housings but given the situation I can expect this to happen at some point.

So now I am debating between three turbos: another GTX3071R (the hysterical way it builds boost has been addressed so no creep, no nothing, all is perfect), a GTX2971R or a GTX2976R.

The 2971R is supposed to spool a bit sooner than the 3071R while flowing about the same on the top end, while the 2976R has the inducer and exducer wheels of the same size as the 3076R, while it should also spool sooner but I have no clue by how much because the compressor maps are missing from the Garret site for the 2971 and 2976 turbos.

I agree the choice is hard as well as emitting reliable opinions about this. However, if I can end up with the top end flow of a 3076 and the spool of a 3071 by purchasing the 2976 then I'd get that. Or if the 2976 will spool/respond slower than the 3071 then I can retain the top end flow capabilities of a 3071 (which are satisfactory for a FWD car) while having a better spool by purchasing the 2971.

So what do you guys think?

P.S.: my choice will be only between these. I can't get an EFR kit (which would give better overall performance) simply because I'll have to mess with at least the exhaust manifold, downpipe and test pipe and I may not pass the emissions test.