i was just planning to get one of these but i dont know which one is better, thxs

 

depends on the application.

T51R is definantly bigger and you will notice more gains at higher boost, but more lag, I would think

T04Z is a great turbo for a street car. I have a T04R, which is basically the same except it is not ball bearing. It isn't too laggy (wastegate opens @ 14-15 psi @ 3800 rpm) and makes good power on top.

There are way too many factors to consider - provide some detail as to what you want to acheive with the car. I would say the T04Z is a better street turbo, the T51R is big and designed more for drag applications - but im sure it would pull pretty hard

 

oks thxs you! =D