I bought one of these MANY years ago to try it out and prove or disprove. Put it on my H22A1 Prelude and dyno'd before and after. Low end, did improve about 1.2-1.3hp, that was up to about 3000 rpms, after that, I lost hp, about 1.4-1.6hp from about 4000rpm to redline. FORGET ABOUT IT.
most of that type stuff does nothing more but create a Placebo effect. you hear some more "noise" so you think POWER!! i remember years ago having my motorcycles on a dyno and seeing these guy come to the shop and throw any pipes on and expect monstrous gains.. then get pissed when they actually Lost power! of gains 1-4hp.. and the pipes were $700+ !! alot of the time it was because it wasnt a well balanced system.. they added just pipes and nothing else.. but the increased noise made the believe that gained all this insane Horsepower.. lol