the biggest turbo is bigger than your house.
the tXXX is just a size than Garret uses to define its product... the same way Mitsubishi uses 14b, 18g, 20g, etc...
basically, the bigger the number, the bigger
but put an imagineary deciaml place in there...
t25 is NOT bigger than a t3.. think of it as 2.5
t25
t3
t4
t66
t76
t88