Upgrading help.

Why does everyone think intake/exhaust is he way to go with a slant six. This is a low compression engine (7.8-8.0 to 1). The most improvement for the money, is to raise the compression. Pull the head and mill it between .060 and .100, depending on the results you are looking for. You should take measurements, and find out how much to mill, to get the CR between 8.7, and 9.2 to 1 for a street car. While the head is off, you can do a valve job (if necessary), and a little pocket porting in the bowls. It is a little more work, then a manifold change, but actually should cost about the same or less, and will give better results. There is no downside to doing this. It increases engine efficency, increases torque, horsepower, and fuel mileage (have your cake, and eat it too). After that any other mods, like cam, manifold (intake/exhaust) carb, will have bigger gains.