[signal_23]

I have a set of Hooker Competition headers (1 5/8) and was planning on using them on my 455. I have been told I should step up to the Super comps (1 3/4), what does everybody think? I have read a lot of good information and thought I would throw the question out. I am running a Torker II intake, Holley 750 vacuum sec., 6x-8 ported heads with 2.11/1.77 valves, 9.25:1 compression, and 3.42 gears. It will be in a '80 T/A, so it will weight bout 3800lbs. I hope to make around 425HP and run in the low to mid 12's. The car will be mainly a street car, with occasional trips to the track.

[signal_23]

I have a set of Hooker Competition headers (1 5/8) and was planning on using them on my 455. I have been told I should step up to the Super comps (1 3/4), what does everybody think? I have read a lot of good information and thought I would throw the question out. I am running a Torker II intake, Holley 750 vacuum sec., 6x-8 ported heads with 2.11/1.77 valves, 9.25:1 compression, and 3.42 gears. It will be in a '80 T/A, so it will weight bout 3800lbs. I hope to make around 425HP and run in the low to mid 12's. The car will be mainly a street car, with occasional trips to the track.

[Torment]

I'd guess it would make very little difference as long as they're both 4 tubes.

[Steve C.]

If your heads have been flow tested use this. From zillions of dyno testing hours David Vizard offers this formula to determin exhaust pipe inside diameter. It can be used to make near-optimal primary pipe diameter selection.

Take your exhaust port CFM tested at 28 inches (or converted) at your maximum valve lift and multiply this number by 1.27 Then devide that result by 85 (this number is called a FD, more on this below). When this is done find the square root of that number. The end result is the inside diameter. Purchase a set of headers accordingly.
Example: A set of heads with 190 cfm on the exhaust. 190 x 1.27= 241.3 / Divide 241.3 by 85= 2.838 The square root of 2.838= 1.68
Order the appropriate header that is close.

Note: the number FD in the formula means the flow density and for a race application, 80 works well. For a performance street motor use 85, and a regular street motor use 90.

[Larry Navarro]

....if you need to change, use the 1.75" super comps.
many street ponchos don't need anymore than this.
dave sober uses 1.75" on his low 10sec., street car with D-ports.