If you want to make your CB650 Nighthawk slightly louder without going for an excessively loud exhaust, there are a few options you can consider:
Slip-On Muffler: Installing a slip-on muffler can provide a slight increase in exhaust sound while maintaining a reasonable noise level. Look for a muffler specifically designed for your bike model to ensure proper fitment and compatibility.
Baffle Removal or Modification: Some stock exhaust systems have removable baffles that can be taken out or modified to increase sound output. However, removing or modifying baffles can affect backpressure and may require carburetor or fuel injection adjustments for optimal performance.
Exhaust Wrap: Wrapping your exhaust headers with heat-resistant exhaust wrap can change the tone and volume of the exhaust note slightly. It can also add a custom look to your bike.
Air Intake Modifications: Upgrading the air intake system can improve airflow and potentially enhance the sound. Consider installing a high-flow air filter or modifying the airbox to allow more air into the engine.
Sound Dampening Material Removal: Some bikes have sound dampening materials installed in the exhaust system to reduce noise. Removing or replacing these materials can result in a slightly louder exhaust note.
It's important to note that modifying your motorcycle's exhaust system may have legal implications, impact emissions compliance, and void warranties. Additionally, excessively loud exhausts can disturb others and may not be well-received in some areas. Always ensure that any modifications comply with local laws and regulations regarding noise limits and emissions.