If you are going to do this conversion, as I am planning to do into a 260z and as 400zed has already done, I suggest that you also go to hybridz.org . IMO this site is definately the best forum 1UZFE site on the net, and hybridz is easily the best z conversion site around. If you havent already...
Just to clarify, whats the difference between the MP90 and the MP112, and the M90 and M112? Roots and screw-type or just updated models? I understand the different sizes, 90 and 112, but what does the P mean?