Don't touch it.
I would bet good money on the fact that knife edging it won't help at all insofar as performance, and then you make a very thin piece of metal that will be more likely to ROT away under the intense heat of the exhaust! Eventually it will look like an oxidized metal or aluminum tin can sitting in a fire for too long.
IF you had a lot of casting flash on it and wanted to smooth it out then that would be fine to help reduce drag on flow. Even porting for gasket match purposes so that it is the same size as the inlet flange will be fine.
Otherwise NOPE.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black