I would like to talk about the dyno runs made at zhome.com . He has measured the results of some fairly common upgrades that Z fans do to there cars . It is good to see some actual #'s on paper . Manufacturer's way overestimate what the product will improve your cars performance . I have the MSD system listed and was dissapointed to see it did not change HP than much . My car is a 78z after this upgrade I did notice a difference in the cars driving charachteristics . Throttle response was better and it seems to drive smoother at low rpms . I would recomend this to other people as an upgrade, it gave me more results when I put a header and 2-1/2" exhaust . My exhaust sounds great that is worth it in itself . If you read Sports Compact Car they got 15 extra horse out of an Altima 4 banger from K&N intake and new exhaust .