Soaring

Engineers put the stock car together. Shade tree monkey wrenchers figure out ways to screw up a perfectly good engine design. There is a ratio of almost nothing regarding back pressure that is the ultimate goal. What comes in, must go out in simple terms. If the BP is too high, you lose HP. Unless you modify the exhaust system to allow more outgo, then putting more air in will work the opposite direction for you. You increase BP and lose HP. So, yeah, it depends on the mods to the exhaust.