by allowing the engine to breathe better, and being less restrictive, imo, it has the potential for better and smoother running, thus longevity of the engine is increased.
raspy, well a lot of times i have heard headers or a header in this case that will make an engine have a tinny or raspy sound to it. in that case often times a resonator is installed. i was just making sure when a header is installed on the 170, the engine will not sound raspy.