[Christ]

Back pressure does not exist in logical terms. That's exactly what I meant by it.

Literally, back pressure would describe a force which was pushing exhaust back up the exhaust channel, which does not occur. In reality, what most people refer to as "back pressure" is the slowing of the flow of exhaust gasses due to over cooling/over expansion.

It's a burden on my mind to see that yet another person who appears to have some grasp on the engine as a whole is using the term back pressure as though it actually means something that applies to engines, when in reality it does not. A more accurate term would be flow restriction, and that doesn't fully encompass the circumstances either.