I have a 2008 Kawasaki Ninja 650R. I love the bike and have a q2uation about exhaust systems. I have heard bikes with the muffler cut off. The sound is amazing. If you left the pipe like that could it hurt the engine? If so what could be done to prevent damage? I have considered cutting the pipe and welding a megaphone type extension but it would still have no real muffler.

Likely the only permanent damage is to your ears, attracting much more attention of the Thai police and gives you a bad reputation in your community (MooBaan).

Removing the muffler off your Kawasaki Ninja 650R probably won't wreck anything but its performance will be noticeable less the with the muffler. So, if your goal is to make less horsepower, go slower, alienate yourself from anybody around you and get much friendlier with the law enforcement, it's a great idea.

Otherwise, visit a motorcycle shop who sells some aftermarket exhaust system, they have probably a muffler which sounds a bit more muscle without breaking the law.

I'm looking for a exhaust pipe for my Kawasaki Ninja 650R, anybody can give me an address in Thailand?