Rich, I also participated in this article myself with a product of my own, and the article is somewhat misleading. The topic of the gains of the Dutra Duals is well documented by previous testing on the Slant 6 forum, and they average about 8-10 HP over the stock exhaust manifold in other tests. While headers gain considerably more. Gain is still good though. As panic mentioned, the actual gains are somewhat skewed by the addition of many other upgrades.
