What does this mean?

When it says t3/t4 .60 …what does the 60 mean? And what makes it a better turbo? I guess im talking about trim.

thats the a/r of the exhaust wheel. Basically the bigger the number the greater the lag time, but the more efficient the turbo is (within reason.)

EDIT: I dont think thats the trim. They will specifically say “50 trim” or “60 trim.”