I am making an analogy between this and a muscle car. Turning on your A/C yeilds a loss in horsepower between 3 and 7 (depending on the car). I'll call it 5 HP. If you have a muscle car with 350 HP, you won't notice the 5 horsepower decrease. If it wasn't for the cold air blowing in your face, you wouldn't say "gee my car feels sluggish today, the A/C must be on." It is the same with a K&N filter. It will give you 3-5 HP. Headers 15-20 HP, and so on. None of these items will yeild any noticable difference in performance. None of them by themselves will win you a race. So what is the point of adding things like them? Because by themselves they may not do much, but in conjunction with other small increases will add up to a very noticable difference. Once you are done adding headers, roller rockers, cold air intake, power programer, exhaust, and throttle body spacer. By the time you're done you've ended up with 80-100 HP which does make a difference.
So what I'm saying is that 1 db aint going to make a difference on its own. But a gain is still a gain. Other improvements you may be able to make on your system can add up. It may end up adding up to an S unit or more by the time you're done. In my opinion that would make it worth the extra dough. It all depends on what you have to start with.