[rberns]

If you are asking the different between stock TB versus a ported TB (using either a CNC machine or by hand), the ported TB has these swirl like engravings on the inside of the TB near the lip. It's designed to change how the air flows which is has been known to give better throttle response, but not known to give any HP increase. There is also a difference between CNC and hand ported TB. Simple, don't go with hand ported TB because they are known to be not as effiecient as a CNC and also hand porting can be very difficult to get right. A CNC ported TB you can ensure that you wont have any porting issues. Not sure if this helps at all, but I know there are many others around here that can probably give you a more technical answer if thats what you are looking for.