Porting a 80MM MAS

Porting the 80MM MAS of a stock MAF

Has anyone done this and a) how much did it improve or b) hurt? (i.e. Check engine light is now a permanent fixture on the dash or car running rough and too lean). I have found 2 articles on porting this piece of the intake but I am a bit nervous about it and wanted to reach out to see who else has done it and what their experience has been (http://www.corral.net/tech/powerplant/mafgut.htm)

I'm a newbie to the StangNet forums but long in the tooth on Mustangs.

Thanks in advance

Vellines
96 GT