Not really man I was running 16.8 with just an exhaust and intake and when I got my header I started running a 16.2 - 16.0 and with my current setup i'm running 15.7-15.8's really consistent.....the header does make a difference plus one of my friends made 12hp gain acrross the midrange and high in his JDM B16 swap with the Megan 4-1 header and out performed his DC 4-2-1 Ceramic piece of junk....
