Also dyno headers to car headers or any header short of big $$$ ones .5 in the quarter you must be smoking crack! I see a pretty nice street combo no regrets with a fairly flat torque curve.
Of coarse they are, he will be using mufflers with exh. A dyno is just a tool its not the end all be all.He might be really pleased , also not all dynos are equal this one could be stingy.
Look at the track testing between TTI's 2" headers and Schumacher's. There is your .5 seconds. Black and white real work numbers from the same car with both headers.
agreed that numbers don't show the same from dyno to dyno. To me it s a break in and or a tuning tool. Some just want bragging rights.
I can only speak for my engine dyno guy. He uses mufflers on all of his runs. Granted they are an XR-1 design but mufflers and 8 ft of pipe or so none the less.
OP, those CC numbers look fine. I give you credit for checking all 8, I only do one or 2 cylinders!