Originally Posted by crossfirefrank
I think your example is extreme. Maybe you should take a piece of 2 1/4" PVC and reduce it to 2" and blow thru it and see if you can tell the difference. I would think Gary has increased hp rather than decrease it. He went from the restrictive OEM muffler which has baffles, 90 degree bends etc. to a free-flow straight thru design.
the example was meant to be an extreme so it was clear how restrictions work.
as for the muffler, that is true it may actually balance out the loss from the pipe restriction if it is indeed a flow through design muffler. can you look in one end and see through the other?