Originally Posted by Kanga
Karn,I thought that would be the case.People (JUG) keeps harping about needing back pressure otherwise you lose torque,it's nonsense,they wouldn't make hi flow cats and free flowing exhaust systems if that were the case.When I changed my system with hi flow cats and a free flow exhaust the car pulled like a train.
Kanga,
the general rule is that restriction on the exhaust imposes pumping loss on the engine ao by removing it you increase the effective work of the engine. The exception on the rule though is that if you have an engine with large valve overlap then you would lose torque at low rpm as the A/F mixture would escape through the exhaust valve. Of course at high rpm this cannot happen and therefore you take full advantage of the reduced pumping losses.