Methods and apparatus for processing substrates are provided herein. In some embodiments, an apparatus for processing a substrate may include a process chamber having an inner volume and an exhaust system coupled thereto, wherein the exhaust system includes a plurality of first conduits, each first conduit having an inlet adapted to receive exhaust from the inner volume of the process chamber. A pumping plenum is coupled to each of the plurality of first conduits. The pumping plenum has a pumping port adapted to pump the exhaust from the chamber. The conductance between each inlet of the plurality of first conduits and the pumping port is substantially equivalent.