Louder always seems like it's faster. But most pipes make a bike slower. Yeah, yeah, I know about the weight savings. If I had a fuel injected bike, the first thing I would do is synchronize the injectors. Then I would get a dyno run to see how the bike is running. They charge $50 for a baseline run in my area. Just remember that dyno runs are done at wide-open throttle. If you have a stumble off idle when pulling from a stop, or part-throttle problems, it won't register on the dyno sheet.