[MiracleMax]

Want a very graphic representation of back pressure on an engine!

Strap two 10 pound weights to your arms then go about your normal routine.

I always find the back pressure thing interesting. Anything that inhibits the flow of exhaust out of the engine creates extra work for the engine to do, sapping that much more power from the crankshaft.

Exhast systems function just like an intake when it comes to resonant tuning, velocity, ect.

Ideally you want ZERO back pressure with just enough negative pressure created in the exhaust to help draw more fuel and air into the engine without sucking it into the exhuast system (tricky thing to do).

Its interesting to note that most people install headers that are a tad bit bigger than is nessecary. I suppose combining this with a very effcient exhaust system creates very lazy exhaust flow down low in the RPM range, the net effect being a loss of torque at the bottom with the peak being shifted higher in the RPM range where the exhaust system starts to come into its own and reduces the load on the engine or helps to draw more air/fuel into the engine.