The roar of an engine is one of those sounds motoring enthusiasts love, and many a home hobbyist has spent ages trying to tune and retune his car to get the peak performance that comes with a highly charged engine. Others just want to take a shortcut and make their vehicle louder without the tune up. Adapting exhaust systems is the easiest way to accomplish this. If you have a glasspack muffler, one shortcut you can use is to use water to harden the sound-dampening fibreglass inside the muffler.
Drive your vehicle enough to significantly heat up the exhaust system. About 30 minutes of uninterrupted highway driving should be enough to heat up your muffler enough.
Leave your vehicle running so it's sill producing exhaust, and insert a water hose in the tailpipe until it reaches the start of your glasspack.
Turn the water on, and let it run for about three seconds, then remove the hose from the tailpipe. This causes a reaction in the fibreglass inside the muffler, making it rigid and less able to absorb sound. Try not to let water creep up into the exhaust system, as it will react with exhaust fumes and corrode the system.
Drive your vehicle for another 20 to 30 minutes to continue producing exhaust that will flush any water vapour out of your exhaust system. Water vapour will corrode your exhaust system and may also seep into your engine, corroding parts there.
This method only works on glasspack mufflers that are an aftermarket addition to vehicles. If you don't know whether or not your muffler is a glasspack, it probably isn't. Check with your state ordinances that regulate automotive noise. Damaging a muffler may be illegal or force a replacement if it fails an inspection.
Modifying your exhaust system in this fashion will almost certainly contribute to additional exhaust-system corrosion. The fibreglass in mufflers absorbs high-frequency noise, so destroying it won't add low-end rumble to your ride.