The fuel savings claims are "hype"...a part of product promotion that doesn't seem to have convinced anyone in the business except for a bunch of customers that think they have increased their mileage with an Aero muffler. After several years in business, then going public recently, it still appears nothing much is happening in the way of increasing sales to any significant level.
All imvho.
In pennyland, most things are not as they "appear". Know when to buy...know when to sell.