The Dennis Kirk Blog
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We wish that we could offer you a simple answer. We know you’re wondering what kind of exhaust is best for your Harley. You’re probably hoping that we’ll say: “Here, get this! It’s the best on the market, it’ll look and work great and it’s incredibly cheap!” …If only it were that easy. But, life is never quite that simple, and that’s not something we can offer. However, we can offer you what the pros and cons are of the available options. The options that we’d like to cover are slip on exhausts (mufflers), 2 into 1 exhaust systems, and true dual exhaust systems.
One thing that a lot of people like to hear is that they don’t actually have to swap out the whole exhaust system. Slip on exhausts are a quick and easy option. When you buy a slip on exhaust, you are essentially just replacing the muffler section of your exhaust system. It’s fast, simple, and cheap, but it will offer less results, both aesthetically and performance-wise. It can change the sound of your bike, it can change the look, but changes to performance will be minimal at best.
If you are looking to make a more noticeable change, then you should consider buying a full exhaust system. For the V-twin in your Harley, you have two options and one choice before you can go any further. That would be the choice between 2 into 1 exhaust and true dual.
With 2 into 1 exhaust systems, the two exhaust pipes combine to emit fumes through one muffler. Sound will obviously vary depending on the pipes and muffler, but these systems are generally characterized as being higher pitched compared to true duals. These pipes are also typically lighter, meaning you can shed a couple pounds off your bike, especially if you buy pipes made with lighter materials like carbon fiber and aluminum. They generally perform the best at low RPMs, which is where most riders will notice an increase in performance. With that, though, a 2 into 1 system may hinder top end performance.
This design also aids in one other special advantage, a benefit referred to as scavenging. When the first cylinder sends a pulse of exhaust shooting down the pipe, it helps to pull oxygen into the second cylinder. Then, the second cylinder helps the first in the same way, and the cycle goes on. 2 into 1 exhausts can offer a better balanced airflow in your engine which can result in more torque and a smoother idle.
Where 2 into 1 pipes are more common on smaller, more sporty bikes, true duals are more common on baggers and touring bikes. They give your bike a more balanced look thanks to their two separate mufflers, each emitting exhaust from one of the cylinders. They perform best at high RPMs, unlike the 2 into 1 systems, which make them a great choice for those interested in top-end performance. They also provide that stereotypical deep Harley rumble. And if you want the pipes to be louder, you can remove the baffles. But because this removes back pressure, it might hinder performance.
We know what you’re thinking: “What about that wonderful scavenging phenomenon, I want that too!”. Well, you’re in luck. Dual exhaust systems can actually be bought in a configuration that is best described as 2 into 1 into 2. Basically, the pipes combine for a short time before splitting again, meaning you can have that classic true dual look and the increased performance brought on by the scavenging effect.
It’s important to remember that while aftermarket exhausts can make improvements in horsepower, torque, and acceleration, results will vary depending on your current exhaust and the exhaust that you switch to. It’s important to look closely to see what differences exist between your new and current pipes. Attributes like shape, diameter, header design and scavenging ability are all worth noting as you consider the amount of improvement you might actually see from your new exhaust.
When you make the change in your motorcycle’s exhaust, the work doesn’t end there. If you’ve succeeded in increasing the airflow out of your cylinders, then the fuel/air ratio should be changed as well. Without a change, your engine might run lean, and you’ll need to either re-jet or remap your motorcycle. This probably isn’t necessary if you only changed the muffler, but the bigger the change, the more important it will be.
You might have been hoping for a more straightforward answer, but a straightforward answer simply doesn’t exist. But, on the bright side, while there is no right answer, there is also no wrong answer. So, do your research, weigh the pros and cons, and rest easy knowing that your new exhaust will work as sweet as it sounds. If you have any tips for your fellow rider, don’t be afraid to make them known in the comments below.
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