So good I later bought another one for my wife's car. Welding, excellent sound on 4-cylinder Honda and Toyota engines (4AF, D16, F20C). The muffler does not hum, but is significantly louder than the normal muffler. I installed them by cutting and welding/angling the original muffler (like you might see on the R34 Kakimoto tailpipe). The muffler has no screw hole to install the muffler. I would buy again and recommend.