Before we give you the run-down on this supercharger port we'd like to point out a few things about our ported blowers in general:
Our ported superchargers are proven on the dyno, street, strip and runway.
We rebuild EVERY blower that we port.  EVERY ONE.  New bearings/seals etc.
Many shops out there that sell "ported superchargers" are complete junk.  Just beware of what you're getting.
The LT4 CNC race blower port is max-effort CNC treatment on your 1.7L LT4 blower followed by a by-hand round of inspection and final polishing.  We rebuild parts of the LT4 blower case with a proprietary epoxy process to actually expand the space within the ported blower to allow for more air throughput.
Beyond porting the LT4 blower itself we do a CNC porting treatment on the stock LT4 snout using the same proprietary epoxy process.  Additionally, we port the LT4 snout to create a profile that easily accepts a 102mm/103mm throttle body.
Attention is paid to the case as we play with rotor timing to help setups with large cams and large air volume requirements. This upgrade typically picks up 70 - 90WHP on your "typical" build but its not uncommon for a radical setup to pick up 80-120WHP.
Our process for the blower porting includes:
LT4 blower tear-down
Strip LT4 blower of all bearings
Inspect bearings and blower case for flaws
Reconstruct the LT4 blower case and snout
CNC port the LT4 blower and CNC port the LT4 snout
Perform manual ported LT4 blower finish cleanup
Bathe LT4 blower and snout in our Aqueous parts washer
Install new case and snout bearings
Install customers hub and pulley (or a new LT4 pulley and hub can be purchased)
Fill rotor pack with new Eaton fluid
Install new manifold gaskets for a secure fit to your cylinder heads