Check what your blower clearances are (rotor to rotor/rotor to case/rotor to endplate) and adjust accordingly to turbo blower clearances. I used a sanding block to remove material from the rotors on my 4-53T. My 4-53N blower was already somewhat worn, so removing the high points on the rotors was basically enough to get mine to turbo clearances. We aren't talking huge material loss here, we are just removing enough material so that the rotors do not swell and hit each other when subject to heat and boost from the turbocharger. A 3-53N blower has 0.010" clearance between the rotor and case at the air inlet side, 0.004" on the block side, and 0.010" between the two rotors. A 3-53T blower has 0.012" clearance between the rotor and case at the air inlet side, 0.006" on the block side, and 0.012" between the two rotors. Just an extra 0.002" of clearance is all that is needed. Consult your 53 series service manual, Section 3.4 pg 10
Chris