Quote:
Originally Posted by taxonomy  I think if you put a 1 HP shop vac in blower mode to the intake and of an exhaust it would blow through pretty easily, even a "tight" stock exhaust. It's not like you're using up gobs of HP forcing air through teh DOT pipe that you suddely win back when you take a sawsall to the muffler. |
While the resistance to low flow may not change much, removing a baffle can and does affect the percieved backpressure the engine observes by removing a reflecting wave.
This is why there is a trend for larger and larger diameter OEM canisters now, more flow/hp while retaining sound deadening ability.
And there are bikes that respond greatly to airbox modifications without 'destroying' their midrange or dyno curves. Again, my ST3 is a great example, three holes in the airbox lid, positive gain across the board. I could have gone with a kit 'lid' that basically eliminates the top and just provides enough of a ring to retain the air filter for larger gains, but I ride in the wet quite a bit, so I reduce liquid water intrusion significantly by retaining the front of the lid.
I have seen midrange suffer on a bike where the airbox was removed to make room for pod filters, but the gain on top provided what that rider wanted so who am I to say he's doing it wrong?