But there is more to power than flow. How about velocity? Two different ports nearly the same flow, but one is quite a bit smaller and better designed. Surprised at the exhaust flow on the 516 with those tiny 1.60" valves...
Further, chamber shape/design is very important as well, and this is where (in my opinion) the old B/RB just fails hard. If i was building an engine with zero deck i think the Magnum would shine even brighter in this regard... but thats just hypothesis.
The numbers above are intake at 2 different lifts , not exhaust . the stock 516 exh at .500 lift was something in a 135 range ...
Well that was a brainfart bad enough to smell... Hey, its late and i should be in bed.
How does the stock 516 exhaust compare to the 360 Magnum then?
It's all there in the links I posted, but here you go!
516 exh .5" 138.2 CFM .6" 139.4 CFM
Magnum exh .5" 148 CFM .6" 150 CFM
...and just for kicks, the much maligned 906's
Intake @ 0.5" 233.9 CFM @ 0.6" 235.3 CFM
Exhaust @ 0.5" 155.2 CFM @ 0.6" 157.6 CFM
..and yes, I know that there is more to head performance than flow, though it is the number that dictates maximum performance levels. As far as the Magnum's better exh. vs. the 516's better intake numbers... probably depends on exhaust, cam, etc.
probably depends on exhaust, cam, etc. 
