From what I have seen and been given to understand, anything that removes restrictions from the exhaust system post-turbo will improve economy/power. Since a diesel doesn't need a certain level of backpressure to function, like a gasser would, anything you can do to get that exhaust out of there and gone is a good thing.
Larger downpipes and exhausts can help the turbo spool faster, lower EGTs, and improve fuel economy, though beyond 2.5" it seems you begin to run into diminishing returns, less benefit for the additional area than you saw in the initial step up from stock diameter.
Topic: newbie question (Read 2011 times)
