I am looking at a 78mm throttle body and is ported, is this quite a bit bigger than the 5.3 stock one?

 

Stock is 78mm on 4.8/5.3/6.0 trucks. I believe ported ones are better judging by my own personal results with modifying them, but others disagree. It depends on what extent that the TB has been ported/polished though. Some people polish the aluminum to a shine and call it good without removing the tumble lip that's in there, or without removing the front half of the throttle bar... without those two things polishing it is useless.

Also, ask what they used to port it with. If it's a dremmel job, back away. A dremmel would take HOURS to a proper job and would most likely end up with a half ported TB at best.

 

what is the proper tool to use to port a throttle body or can a private individula even do it themselves