Cylinder Head Down Nozzles?

[TurboTerry87gn]

I was looking at some AllPro heads and one option was down nozzles. What are they? Something to do with the exhaust port?
I can't find anything on the web about it.

http://www.allproheads.com/images 08/Web 2008 Cat2-08.pdf

 

[Louie L.]

I "believe" its something they use on roundy round applications. For street driving and drag racing its not needed.

All Pros are some of the best 23* heads out there. But If you are looking at 1000 to 1200 hp, regular 23* heads will do the job and save you big $$$

 

[Alky V6]

I think those are used on alcohol engines. Popular in the circle track scene.