I agree with all of the above regarding wire size. There is, however, a set up with dyno proven results to increase spark and power. After reading the article in the last month's edition of American Bagger magazine I installed a set of Nology Hotwires on my 03 FLHTPI and there is a very definite improvement in power. If you look for them online be sure to search nology.com which is the manufacturer and nologyhotwire.com which is a retail distributor.