If the mufflers are straight through glasspackeddesign, some of the glasscan blow out leading to a louder muffler. If the muffler is a metal "chambered" muffler design...no it will not get louder.
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Rick 07 GT Prem: Alloy, MT, 3.55's, Steeda CAI/Xcal2 w/Brenspeed 87, 89 & 93 tunes, FRPP Stingers, 275/40/18 Goodyear Eagle F1 All-seasons on SVT 2007 Cobras (OE GT500's)
14" shorty, Wheelskin side scoops & qtr window louvers, A-H rear window louvers, SHR honeycomb blackout panel, Sequentials, big black dog in the back seat
It can be true depending on the packing, even the stockers or GTAs have a small about of fiberglass in them so their tone can change but i'd say it's more then a week more like a month or 2.
Even chambered mufflers will change tone over time as carbon builds up on the paltes inside the muffler, the resonant frequency will change causing a difference in sound.
My Corsa's seem to be the same as when they were new AFAIK. I've put a few thousand miles on them so I would think they would be "broken in" by now. If they did change volume I can't tell.
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2006 GT Premium Vista Blue Auto
Show: Vista Blue mirror covers, billet fuel door, sequential taillights, tail light trim, grill light bezel, map light accent
Go: Steeda CAI + Carbon Fiber hi-flow elbow w/ 91 Race tune
2x AeroForce Interceptors
Pocket Pod in trunk
Corsa crew member.
Stock wheel crew member.
Soon: Shelby hood pins, Roush hood scoop, side scoops, Kooks LT/cat H, FRPP Hot Rod cams, Alum DS, Steeda Delete Plates
Is this true about exhaust?
