The T4 part of the turbo is the compressor and housing. The exhaust side of the turbo is a T3 yet it is a stage 3 wheel at the minimum which is a little different than your stock T3 housing you are comparing the flange to. Call my friend Chris @ his shop (727) 726-5956. <-- Very good machinest and can make you whatever you need. Leave a message so he can return your call if he does not answer. You can tell him Anthony sent you =-)