The LT1 also uses a variable output oil pump that helps reduce the load on the engine, a plastic intake manifold with tuned runners, and cast aluminum exhaust manifolds designed to act like headers to reduce backpressure from exhaust flow. (autoweek.com)
The new ES comes standard with dual exhaust, which reduces exhaust backpressure at high rpm. (speedsportlife.com)
The EXUP servo is responsible for closing a valve in your exhaust to create a known amount of backpressure in the exhaust system to allow the engine to work in the way it was designed. (mechanics.stackexchange.com)