First off, take a good long look at the stock port design…

Now memorize it. I am sure a lot of R&D has gone into making this port look the way it does so what we seek to achieve is to mimic the stock port design, but make it larger and smoother. Lets break the manifold into four areas, top bottom, left side, and right side. If you look at the bottom of the port like a sliding board, you realize that the air comes in along the bottom, goes up over the ramp, and goes down the other side. Then look at the top. It helps the air on the bottom go fast by being large and open. Now look at the sides. One side is smaller then the other, which lets the right side flow faster creating a swirl down into the curve of the manifold. It's like your rear tires in a turn. The outside tire goes faster to keep up with the inside tire going around a corner. Now that you have my REALLY simple explanation under your belt, lets get to work.

I started at the top (bottom in the picture) and removed all the metal up to the ring where the gasket seals. After opening it up to the ring, I removed a lot of metal to make the path as straight and smooth as possible.

Then to the left side (right side in the picture). I ported and smoothed this to help the slower air from my example go a bit faster. Remember open it up but keep as close to the stock shape as possible.

To the right side (left in the picture), I really went to work. There is work to be done here. On all three of these ports there is a large casting depression on both sides and the bottom of the outer two ports. I removed metal until the walls were even with the bottom of the depression and then kept removing and opening the port, again, keeping the shape close to stock.

Bottom 01 Bottom 02 Bottom 03 Bottom 04
Now to the bottom. You want to make the "sliding board" as smooth and easy to "ride" as possible. I again cut down to the ring of the gasket and then blended it until the floor was as smooth as I could get it and as deep into the port as I could get. I also tried to make the floor flat. I have seen a lot of references to airflow while researching porting and most of them say that exhaust walls should be as smooth and possible for best flow. I have also seen the air like to turn on a flat plane, which is why we want the floor to be as smooth as possible and flat.

Finished 01 Finished 02 Finished 03 Finished 04 Finished 05
Next you want to clean up any areas that don't look quite right. In this port, I didn't get the floor exactly flat so I am going to go back and straighten it out. I also need to open up the port more so the walls are smooth and straight going in. I wish I could reach deeper into the port but I haven't seen any long bits for dremel tools. By the way, I used a Ryobi variable speed rotary tool set at its maximum setting. Have fun porting!