Installing straight pipes on a Harley-Davidson or any motorcycle can have several effects, but whether or not it will "hurt" your Harley depends on various factors.
Legal Considerations: Straight pipes often result in a louder exhaust note, which can exceed legal noise limits in some areas. You may be subject to fines or penalties if you violate local noise regulations.
Engine Performance: Straight pipes can alter the backpressure of the exhaust system, which can affect the performance of your motorcycle. The engine's air-fuel mixture may need to be adjusted to compensate for the change in exhaust flow, otherwise, it could result in a lean or rich running condition. This may lead to decreased performance, reduced fuel efficiency, or potential damage to engine components over time.
Warranty and Modifications: Modifying the exhaust system by installing straight pipes can potentially void your manufacturer's warranty. It's essential to check your warranty terms or consult with the manufacturer or authorized dealer to understand the impact of modifications on your warranty coverage.
Rider and Passenger Comfort: Straight pipes typically produce a louder and more aggressive exhaust sound. This can result in increased noise levels for the rider and passenger, which may cause discomfort, fatigue, or hearing damage, especially during longer rides.
Environmental Impact: Straight pipes often result in increased noise pollution, which can be a nuisance to others and harm the environment. It's important to be mindful of the impact your motorcycle's exhaust noise has on the community and environment.
Ultimately, the decision to install straight pipes on your Harley-Davidson should take into account legal considerations, potential performance changes, warranty implications, rider comfort, and environmental impact. It's advisable to consult with a qualified motorcycle mechanic or dealer who can provide specific guidance based on your motorcycle model and local regulations.