1) first of all, they seem to be converting (marketing term: cooking) their HP and torque numbers to "at the crank" numbers versus "at the wheel" numbers. to my knowledge, they make all measurements on their chassis dyno (at the wheels). converting the numbers makes the increase seem more attractive. from what I've seen, the rest of the industry provides "at the wheel" numbers.

2) to make matters worse, when Dinan quotes a gain, they use the maximum delta between stock horsepower and "modified" horspower. the problem with this is that a lot of these maximum deltas are BEYOND the maximum horsepower point. take for example, the intake manifold for an E30 325i. this manifold is claimed to add a whopping 41HP at 6500RPM yet if you look at the dyno chart, you'll see that the peak total horsepower is actually at 5750RPM and the gain is a significantly lower 27HP at that RPM. now normalize the number back to a rear wheel horsepower number (where they probably actually measured it) and that's more like 22HP-23HP. even 22HP seems optimistic to me considering this manifold appears to be nothing more than the stock manifold with some porting, polishing and a fancy paint job (runner lengths are likely unchanged). even using the normalized number, this is the biggest HP gain that I've ever heard of from a modified stock intake manifold. it's not just this manifold where they measure peak delta (even if outside the max HP range), it's all of their parts. just browse the web site and look at dyno charts. you'll see what I mean.

from a company that is as highly respected as Dinan and that puts so much R&D into their modifications, I really feel that their marketing is borderline unethical.