I don't mean to be blunt or dismissive, but the pressure in the veins/arteries has nothing to do with (a) the thickness/elasticity of the wall tissue, (b) the diameter of the arteries/veins, or (c) the number of (branches of) arteries/veins.
This can either be caused by a more prominent maxilla (upper jaw) or a retruded mandible (lower jaw further back than it should be). This causes a discrepancy in how all teeth contact, and can manifest as an increased overjet. An increased overjet can also be caused by a discrepancy in the number of teeth, or the length of the arch.
If you had to rejet because your changing the volume of air passing through the engine then you would have to rejet for different engine speeds. (example: I would need a different main jet for 7000 rpm than I need for 9000 rpm.).What the carburetor does not know is how dense the air is coming into it.n aftermarket exhaust system works by scavaging the cylinder better due to less back pressure. You see when the piston makes the exhaust stroke if you dont have a good flowing exhaust some of the burned gas is left in the cylinder. Then you have less room for new gas and air on the intake stroke.