Cylinder Head Flow Bench?

If this is for your own use you can find the older 10" benches fairly cheaply. The high pressure drop 28" benches are a bit more - if you can find them. But - for the DIYer the 10" bench will give you indicators on improvements much better than guessing, and you can convert them to 28" pressures for comparison although you do lose some accuracy. You can also hunt around and find kits and plans for them to build your own. It's still a couple thousand for everything with a usable software package, but that's pretty cheap given the abilities. If it's for one or two sets - pay for the testing. If it's a regular thing the shop may give you a break. You can also save by only flowing and inside and outside port, and using templates make the others match...