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3.
A type of exhaust. Features a straight through exhaust tube to provide as much exhaust flow as possible (with holes or baffles in it to direct the exhaust into the packing) that is surrounded by a steel wool or fiberglass packing (sometimes both, varies by manufacturer) to make it relatively quiet considering its a straight through exhaust. Also look up fart can performance exhaust. Sometimes called cherrybombs because it was a major manufacturer of the exhaust.
"The fart can is the same thing as a glasspack"

"Both the glasspack and fart can exhaust work on the principle of absorption"
"The glasspack enables exhaust to flow better than most chambered exhausts"
by TheFlacker99 December 13, 2012
 
1.
Mufflers that are packed with fiberglass to muffle the sound. They come in different lengths. The shorter the glasspacks, the louder the car.
When I get my Corvette I am going to put glasspacks on it.
by OneBadAsp October 24, 2006
 
2.
A noisy, inexpensive muffler design made with fiberglass surroundings and stainless steel. Also referred to as cherry bombs due to a manufacture that produces glass pack mufflers.
When I get my Jeep Wrangler, I am going to put a glass pack muffler on it
by goods_25 September 27, 2009