This is something you can do at home yourself, cause many places will cost you a arm and leg to do this. It will give you more horsepower, fuel efficiency. Making sure the heads are clean, spray them down. Put the exhaust header on, mark the inside with a marker, take off the header. Now using a grinder wheel, grind it down to that line smoothing all the way in the valve wall. do that all around and you will have ported and polished your heads.