cheap down tube?

Im just a FNG but have just done a lot of research on this. I consider 4" on a stock or moderately modified engine to be overkill and have a possible loss of low-mid range power. Ive been speaking to some header companies and to a company that makes race cars with turbos. Im sticking with a 3.5, which means I dont have to buy more pipe since my factory back is already 3.5.