Hey guys…just recently since it started to get cold (below freezing temperatures), my engine has been running louder than before. It’s a ‘94 900 Turbo with 199k km. It sounds as if there would be a hole in the muffler, but the sound is coming from the engine bay. I can also feel stronger vibrations in the gear shift knob, particularly at rpm’s greater than 2500. And this happens even after the engine has warmed up. Does anyone know if this is normal during cold outdoor temperatures? Or could it be due to an actual leak somewhere in the exhaust? I appreciate any feedback. I've also heard from some people say that they're cars run louder when they put in a K&N air filter, which I have one. Could that be it?