Wynn's, STP, NOS and Hot Shot was tested on a dyno by "5th Gear". Power output was DOWN 2% for all of them. But STP was the real winner, it was DOWN 6% at wide open throttle. But you can count on one thing, the web sites for these products will positively conclude they 'really really work', honest.
I have a hunch there may be a few 'boosters' that actually DO work. But relying on a sales outlet for the product, the company itself or 'testimonials' for data just isn't reliable information.
There is, how ever a 'pill' that improves gas mileage, it looks really good. I saw a great clip of it on U-Tube, so it must be OK.
