can someone please tell me 'what the crack is' so to speak

i want to know how a t3 a t34 and a t35 differs and what ar i am looking at when specing a chip on the motorsport developments website

on the site it states for stage 3 a .48 .55 or .63 housing is required

the turbo i have been offered has .48 exhaust and .60 compressor

would this turbo do me right?

general info so i have a clue what the numbers and different turbos are would be nice

i understand that a t34 is a t3 turbine and t4 compressor???

so what is a t35?

also some turbos i have seen that are t34s have an actuator mounbt cast into the compressor snail but use the standard actuator mount of a t3 for example>>>why?

cheers