A: Quiet spools are about half as loud as straight pipes. Actually, they are closer to the muffler side of quiet than straight pipes, maybe a shade quieter than halfway. They still have a good rumble and crack, though. Quiet spools have the internal muffler welded in them, so concerns about rattling or coming loose are not right. They are also totally bolt-free, so visually a true straight pipe setup or a quiet spool setup would look exactly the same. – Bryan Martin, 4 State Trucks
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