X pipe H pipe or side by side

I'll maybe try to explain in a way that make's it a little easier to understand, without going too technical about scavenging and its effect on engine performance and how important it is to your system. Maybe even put a canadian twist on it for yah.

Think of your headers. Why do they work? Because they allow the "pulses" of the exhaust to not slam into each other when they reach the end of the runner. They merge like traffic on a highway. Everyone happy. Everything flows along nicely.

Now, think of the noble canadian goose. Why do they fly in a V? Because, the drag is reduced for each bird the farther back it goes right? Think of your exhaust as the same. Each pulse in front of it helps "pull" along the one behind it. Like our merging traffic, except as you merge you latch onto the vehicle in front of you and use less power to travel. While also pulling the vehicle behind you that just latched onto you.

This "pulling" effect, is scavenging. And will reach back into the cylinder itself through the exhaust valve. If it is strong enough and your exhaust is setup properly. On high end systems scavenging has been shown to help clear the cylinder of burnt exhaust gases, pull in more air/fuel (with proper cam overlap with the exhaust and intake open at the same time) and help the engine run better. If your exhaust and intake valves are open at the same time the exhaust will pull through the intake right? There is the vacuum from the exhaust helping to fill the cylinders. It can't do that if it is fighting itself. Merging the exhaust just amplifies that pulling effect. More pulses pulling more pulses. More cars pulling more cars. More geese pulling more geese.

If any of that makes sense.