i just had a stainless steel dual tip installed onto my muffler..and welding was fine...started up the car..sounded great...revved up the engine and this whistling sound came out REAL LOUD..it sounded horrible...car sounds great until i floor it...the whistling sound comes..sounds bad....i dont know...we covered up one of the outputs with our foot and you couldnt hear the whistle if you rev it up so we figure its the tip...i dont know...i think maybe muffler shops are closed tomorrow since its MLK b-day...but if not ill see whats up...just liked some input...doubt this has happened to anyone...