I go 4 fingers down from the collar on the front, and just under the front collar impression on the backside of the shirt. everyones fingers are different so I measured mine and the 4 fingers measure 3.5. I also use my left hand to guage where to put left chest logos.
Grey noise then, has a sound frequency that, if translated to a light frequency, would roughly be the color grey. Grey noise is a random sound that is distinguishable from other types of sound because it sounds the same, to the human ear, at all frequencies.
2. Exhaust is louder than normal. Loud exhaust noise is usually the result of an exhaust leak that commonly occurs in the muffler as opposed to the exhaust components located near the engine. As engine exhaust flows through the exhaust system, it is contained and eventually flows through the muffler.