Recently, I sat down with Billy Boat - President of B&B Performance Exhaust and asked him about developing exhaust sound. This is what he had to say.
How do you achieve a great exhaust sound?
One of the first things we try to do is establish a baseline with the factory system. That will involve doing decibel readings at idle and at cruise – trying to determine where the factory system is, and then working on the performance system from that baseline. Most factory systems, due to regulations, are too quiet for the performance customer. In general they are looking for a deeper, throatier tone with more volume. Yet at the same time we keep the resonation out the system at cruise - which is very important for a pleasing driving experience. The way we go about achieving that sound is look at the pipe diameter from the factory and we look at the muffler. In general we go up on the factory exhaust diameter to give the tone a little more bass and little more volume. I think the real key is to design each muffler specifically for each application. So, we are not trying to take an off the shelf 2 ½ inch packed muffler and apply it to every application. We are actually looking at the muffler shape, size, and length and designing a muffler that is specific for each application. That way we can the right combination of absorption qualities - which help build that nice throaty tone, and cancellation - which takes out the resonation at cruise.
How long does it take to develop the right sound?
How long it takes depends on each application. Sometimes you can design a system and right off the bat you have a sound you are happy with. Other times you have to go through five or six iterations between pipe size and muffler design trying to get the right sound. Obviously the right sound involves not only that nice deep tone, but also keeping resonation out at cruise. So, the perfect system is louder when you accelerate - when you step on it when you want to hear it. Yet, while you are cruise it is quiet so you don’t get drone from the exhaust while you are cruising.
What are the challenges of creating the right sound?
I think the biggest challenge is achieving the happy medium volume for the majority of the customers. Everyone has their own idea of what loud is - which is one reason we build at times different sound levels of systems. For example on the C6 Corvette we have three different sound levels. So, trying to find that happy medium and trying to satisfy each customer’s desire for the right sound is the challenge. It’s like offering vanilla, chocolate or strawberry - we try to do the same thing for the customer with exhaust sound.
Does developing great sound hinder or help power?
We are always looking to make sure that we are increasing horsepower. Dyno testing and development is all part of the process of developing that right sound. You can build a muffler sometimes that might sound good but doesn’t perform. And that’s not an option for us. Not only are we making sure the sound is good we are also testing performance to be sure we are increasing performance of the car.
Is it a challenge trying to eliminate drone while creating a pleasing exhaust note?
One of the problems of going purely with a cancellation muffler – which is what some of our competitors do – is that you create a tinny sound – something that doesn’t have that deep bass tone. That is one of the challenges – trying to get the best of both worlds. The fact is that you need a combination of cancellation and absorption and in order to get a deep tone, yet be able to kill the drone at cruise.
What are the considerations in developing sound for a V6 versus a V8?
The number of cylinders of an engine has, and the way the engine fires definitely affects the sound the engine produces. We are constantly getting customers that want us to make their V6 Camaro sound like a V8 Camaro and unfortunately, that is really not possible. You try to take everything in your arsenal that you know about developing sound and apply that to other applications. You can try to get the tone of the V6 closer to that of an American V8 muscle car. You can help it, but unfortunately there is nothing that sounds like a V8.
How do you decide if the sound is right?
Sound is very subjective and what is right for one person may not be right for another person. The real key is being able to find a sound level for an application that will meet the majority of the customers’ expectations, and then you can always tailor it up or down for the customer that might want something different.
Which exhaust system are you most proud of for the sound achieved?
I have been driving a Cadillac CTS-V as my daily driver for many years, and I think that system has one of the best tones of any system we have ever built. Many times we go back that design and that style trying to get to that sound. I can hardly go through a drive through anywhere that the guy at the window doesn’t say “Man your car sounds great”.