Good one - very little to pick on. I agree on all points.
1) Less back pressure from the exhaust (after the headers) the better
2) Indeed larger pipes are harder to keep it quiet (but who cares -
![Laughing :lol:](./images/smilies/icon_lol.gif)
)
3) Magnaflow mufflers are excellent for flow with their straight through design.
4) Not using press bends in the pipe is important as it will kill flow. They showed pipes with no pressed bends which is the way to go if your looking for excellent flow.
5) Big street engines rule. They are not using that much cam for the size of the engine. Good setup is that engine.
Glad the boys are doing those videos. I should look at more of them. I just get frustrated with some of the conclusions when little information is provided. This one was a good one and explained well.
Lastly my comment; there does need to be a restriction on the intake and the exhaust. This is via the Valves in the heads - controlled by the Cam - so select the heads and ports sized correctly for the application then make sure the intake and exhaust does not introduced uncontrolled restriction. Mind you once flow reaches the speed of sound sonic choke occurs so I limit port speed to 300 fps while the rest should not restrict the speed further. This allows port flow to be close to desired speed of sound.
Note: There is a point where it makes no sense to go larger - so a 302 with similar rev range would see not advantage from the 3 inch exhaust over a 2.5 inch system. So it is all a factor of volume of air/gas mass as factored in relative to the RPM. Higher RPM means more air/exhaust to flow. Obvious I know but is often forgotten when selecting the parts package for your car.
I will someday think of something clever to say.