FYI: I picked up an Xcceleration/Ramdom Tech axleback for my N/A Baja. (stock was just too quiet ) Not bad. I have had many exhaust setups on my WRX that acted and sounded very differently. The Xccel on the stock exhaust is pretty quiet at idle but deep. Not as nice of tone as a Prodrive on the WRX but close. The Xccel gets louder with rpm unlike other mufflers(not full throttle-cruising). With the rear seat down there is a very slight amount of droning at cruising rpms. Overall I'm happy with it but I can see it getting loud with addition of other aftermarket exhuast pieces.
Nearest issue is the diameter of the axleback is significately larger but the stock gasket is holding up & sealing well even after taking axelback off several times.