When it comes to glasspack mufflers, the common misconception is that shorter ones are louder. This is not necessarily true. It is actually dependent on a few different factors. The first factor is the size of the engine. A smaller engine will typically be quieter than a larger one. The second factor is the type of vehicle. A sports car will usually be louder than a sedan, for example. The third factor is how the muffler is tuned. A well-tuned shorter glasspack can actually be quieter than a longer one that isn't tuned as well. So, in general, it really depends on the individual situation when it comes to deciding if a shorter or longer glasspack will be louder.