1. The diameter of the exhaust system - the diameter of the exhaust system on the performance side determines how much exhaust waste is flowing outwards at one time. When increasing, you're not only increasing the possible flow of exhaust but you're increasing the noise of the engine that you can hear through the exhaust system. Think of it this way, why do you think stock cars are so quiet? One part of it is that they are typically very small in diameter (Example: L61 exhaust system is about 1 7/8" - 2" diameter).

2. Whether or not you have a catalytic converter - A catalytic converters main job is to help clean some of the exhaust waste before it exits into the outside atmosphere. Yes, they are somewhat of a restriction as far as flow but remember, restriction of flowing air (exhaust) = restriction of sound. By removing this, this typically makes things much louder cause of the restriction being removed from the exhaust system.

3. What kind of muffler you have - The kind of muffler you have can actually make a good amount of difference as to the overall sound of the exhaust system but it's just one piece of the puzzle. If you look at canister mufflers, they are known for being "straight through" and people automatically assume that this means "less restriction, more power". Being that it's straight through, it doesn't deaden the sound of the exhaust (or deepen the tone) like an oval style muffler typically would. As far as the power differences, this is up for discussion but to be completely honest, if there is any difference, it's so small it doesn't matter much in the big picture of performance.

4. Resonators, whether you have one or not and the size of one - Resonators are a very key part of the exhaust system as far as sound quality. Stock exhaust systems sometimes can have 1 to 2 resonators on the exhaust system to give it the sound quality they are looking for but at the same time, not being a major restrictor on the exhaust system as far as flow. The rule of thumb is the larger (longer) the resonator, the deeper your exhaust will be...the smaller, vice versa. From an aftermarket point of view, many companies sell resonators in all different diameters and lengths. On the opposite side, if you choose not to have any, this will of course result in a louder and possibly "raspier" sounding exhaust system.

5. How many bends you have - The more bends that are on your exhaust system, the higher possibility of backpressure being created. Backpressure is basically restriction...restriction (once again) results in lower exhaust tone. Now, I'm not saying to you to make as many bends as possible, this is all in theory and the number of bends you have is probably the last resort or way to try and get a lower toned exhaust system. Incase my explaination of restriction didn't make much sense, when you have a flow of air (in this case exhaust) make a sudden change in direction, this slows down the velocity of air. Remember, sound travels as well.

6. Whether or not you have any exhaust leaks - An exhaust leak is basically an abnormal exit or disruption in the exhaust system. Example, if you have a hole just before your catalytic converter from it rusting over, this is an exhaust leak. This exhaust isn't going through your whole exhaust system which in result isn't going through all the devices that all help lower the tone, so this will result in a louder exhaust system. Also, an exhaust leak is a disruption as far as the velocity of the exhaust which will result in a loss of power.

7. The type of manifold or header you have - Basically works almost the same way as the diameter of the exhaust system if you're messing with aftermarket headers but in this case, you're talking about each individual runner and the size of the collector at the end. A stock exhaust manifold will of course be more restrictive and result in a lower tone.

8. The type and size of the engine - This is basically a given.

That's basically it. It's relatively simple but complicated to a person like Twentyeggs that just thinks he knows what he's talking about.

Also, aftermarket companies do nothing more special to their exhaust system than the local exhaust shop that buys the right parts and has everything bent and welded together. Not saying that custom is always the way to go but it is something to think about when you're paying $600+ for an exhaust system from a known company when you can go down the street with the right "know how" and the right parts combo installed to replicate the same nice deep tone.


Something else to consider, adding mass to your exhaust system will change its resonance frequency for sure. Manufacturer have been doing it for years and they wouldn't pay extra to add weight on a car just for fun. Here are some examples:







Hope this has helped.