Well all of them actually, both exhaust and intake. if you look at the inside radius of each of the port runners, you will note that they are either close to a water jacket or an oil line. Just keep these areas in mind when removing material. Most likely you will not be removing nearly as much to compromise the jackets but it doesn't hurt to practice caution here. If you do remove to much material in these areas, you may not break through to the jacket but the wall will be to thin and could crack later on from exhaust heat. It is probably better to not remove any material from these areas and focus on the outside radius of the runner and the mouth area. Then polish the entire runner once you are satisfied. :tup:
The key to a good port job is to give the flow of gasses the path of least resistance and also to give it more volume. Try to imagine the flow through the head and what obstacles the gasses may encounter along the way and deal with them individually. Take your time and be steady handed and don't just go in removing material without thinking about it first and visualizing the flow past that area
Good luck with this and I am looking forward to the final results!
