Boss side pipes definitely not too loud without the restrictors, in fact I bought my '13 Boss used and assumed the plates were still in based on the sound. To my surprise, when I took the side pipes off, they were already out! Very nice sound with them out, and a very pleasant burble at cruise speeds. One thing I didn't like was the motorboat sound when I backed out of the throttle when using TracKey, so added a restrictor plate with a 3/4" opening instead of the stock 3/16", and the sound is perfect. When not using TracKey, the motorboat sound not near as noticeable on deceleration. One of the beautiful things about Ford's system is the ability to tune the sound thanks to aftermarket restrictor plates with different size openings.