I'm running a 553 on mine. I was looking for a 573 but this was the only one that came up at the time. After looking at Ted's testing of the different manifolds I'm satisfied with what I have.

Dan      Kingman Az.      86409

I have both Edlebrocks but haven't run them on my engine yet. The 553 I have was port matched to fit the bigger port heads. I think the difference is about 1/16" on each side of the port. This was done at the margins of the intake where it meets the head and doesn't open up the full runner length. Based on Ted's thorough just completed test the 553 actually is a bit better for street driving. The 573 moves ahead a little at higher rpm. If you are just running a street application and not racing looking for every bit of high end horsepower/torque I think the 553 would be fine. You can scroll down the technical page to find the test results, 2nd page I think, or do a search for 3x2 intake test results or use the link below.

http://www.y-blocksforever.com/forums/Topic40554-3-1.aspx

Mark

57 Black Tbird 312/auto

Hi,

I know the 553 has smaller ports, but how much smaller than the 573 and can a 553 be opened up to match my heads.

Richard