The Vang Comp System is a lot more than just ports, although that is all you see on the outside.
The VCS consists of back boring which opens up the bore and creates a choke where there may not have been one before. The forcing cone is lengthened.
And then of course you can have the system with or without ports.
I have been doing the VCS under licence in Canada for 3 years or so. More info is on the vangcomp dot com web site.
Casey