Harley-Davidson motorcycles are often associated with a distinctive and iconic sound, characterized by a deep, rumbling exhaust note. While it's true that many Harley-Davidson models can produce a loud sound, it would be inaccurate to claim that they are universally the loudest four-stroke motorcycles. The sound produced by a motorcycle's exhaust system can vary depending on several factors, including the specific model, modifications made to the exhaust system, and the rider's preferences.
There are other motorcycle manufacturers that produce models with equally loud or even louder exhaust notes than certain Harley-Davidson models. For instance, some high-performance sport bikes or custom-built motorcycles may have exhaust systems designed to produce exceptionally loud sounds.
It's important to note that regulations regarding motorcycle noise levels vary across different countries and regions. Many jurisdictions have specific noise limits that motorcycles must comply with, and excessively loud motorcycles may be subject to fines or penalties. Therefore, it's crucial for riders to adhere to local laws and regulations regarding motorcycle noise.