So Cab, do you really think that in your example of going from 109 to 117 mph was because of the restriction of a perfectly good 2 1/2 exhaust system and nothing else? What is that, like 80 hp on a pretty mild motor?

I have more than one example of going from a 2 1/4 compression bent system to open headers that netted 2 mph in 12 second cars.

Obviously your experience is your experience, but logic suggests to me that possibly something else was at play in your example.