[NYPD]

I'm not a tough teacher like Qwiks so I'll give one link. These guys are the cream of the crop when it comes to porting...they know their stuff. On top of the following article I spoke to a friend in Quantico, VA and he told me that ported firearms only lose around 5% to 8% of their muzzle velocity.

http://www.magnaport.com/hgun.html