back pressure

i hear it all over the place, "u dont want that big of a pipe or else u will loose back pressure." what do u need back pressure for? i figured u would want the least.

check the open header exhaust, johnny explained it, to sum up, the backpressure allows a greater velocity at which the exhaust can leave hte pipe and in turn create more power

On naturally aspirated engines, backpressure is a necessary item. Backpressure and piping diameter create exhaust velocity. By making an exhaust too large, you will lose your back pressure and exhaust velocity. That will result in lost power.

Forced induction engines are a different beast though. Because of the excess amount of exhaust gases, the gases must be expelled from the piping as quick as possible, turbo'ed engines especially. Truly, the best exhaust for a turbo'ed engine is none at all.

thats what johnnybgood said