Originally posted by nbn22385
ive heard hondas need some back pressure or else power can actually decrease.
No no no no no no no...
Back pressure is a side effect from reaching a reasonable compromise between maximizing exhaust velocity and CFM of exhaust. Engines do not "need" back pressure, it just happens that no exhaust possible will flow 100% of the exhaust an engine produces while simultaneously keeping exhaust velocity high for best scavenging effect, without generating some back pressure.
Back pressure impedes the flow of exhaust, and on a little four cylinder, you want to move the exhuast as efficiently as possible so that the maximum amount of fresh air/fuel mix possible is brought into the cylinder for combustion.