Joe, I really wish I could tell you, but I bought them used from Michael Pollack (Carcrazy455). They had originally been done several years ago and he remembered them being in the .290's up to .600. Unfortunately he couldn't find the flow sheets when I bought them. He also had some more work done on them when he freshened them up not long before they were to be replaced with aluminum heads. They have raised intake ports and the SP1 is matched to them. I wish I had taken photos to show the difference between them and stock heads, but it's about .25 of an inch higher. He had went mid 10's with them in a 12.2:1 motor on his car. Rick Henderson and I got the car going late this year and there was only one race, but I couldn't make it. Hopefully I'll find out what it runs in a few months. At this point, it still has the 2.56 open rear in it too though.
