Generally speaking, the KTM RC 390 tends to have a louder exhaust sound compared to the Kawasaki Ninja 300. KTM motorcycles, particularly the RC series, are known for their aggressive and sporty exhaust notes. The RC 390 typically produces a throatier and more pronounced sound due to its higher displacement and performance-oriented design.
On the other hand, the Kawasaki Ninja 300, while still having a sporty sound, is generally considered to have a quieter exhaust note in comparison. The Ninja 300 is designed as an entry-level sport bike and is often aimed at riders who prefer a more refined and balanced riding experience.
It's worth noting that the exhaust sound of a motorcycle can also be influenced by various factors, such as aftermarket modifications, the specific exhaust system installed, and the rider's throttle usage. Additionally, local regulations may limit the noise levels of motorcycles, so the actual sound produced by these bikes can vary based on factors like geographical location and regional legal requirements.