P-51 Porters What is the best header pipe exit?

We may build a new set of headers this year and I was wondering what the best exit angle on the flow bench has been for stock P-51 heads. What is better, 90 degrees to the head, angled slightly upward or angled downward? 512 ci. 2 1/8" pipes, Jon Thee flanges, probably 4" collectors.

IMO either 90* to the head, or angled slightly downward. Bottom line is, the fewer the bends the better.

Uncle Charlie

What charlie said, Come as far off the head as you can up and out the turn down with the widest radius bend you can fit.

Good to know as I will be having a custom set of headers made......

My headers i built for my street heads fit the P-51 port nicely.................they are 2 1/8' stepped to 2 1/4" and then 2 3/8" right before entering the collector. I used a set of Flanges from Jon Thee and he scooted the opening around until if fit the port real nice. I plan on making a new set, size will be determined after the dyno session so we'll see................I may sell these headers I have.............