Conventional wisdom used to be that boxers are "naturally-balanced", (the movement of the pistons cancels out), so less vibration, and that the design provided for a lower center of gravity, which could aid handling in the vehicle.
Beyond that, a lot of us appreciated the "boxer rumble", a sound that was notably different from a whiny inline four. That, of course, is subject..and no long applies for the newer cars. My BRZ and your WRX now come with equal length exhausts, so not much rumble to speak of.
I don't know that your car would be any louder than any other 4 cylinder. You really want a muffler delete? My car with the 4 inch axleback is plenty loud. My VW-based sandrail had no muffler..but you know...it was a sandrail.
Beyond that, a lot of us appreciated the "boxer rumble", a sound that was notably different from a whiny inline four. That, of course, is subject..and no long applies for the newer cars. My BRZ and your WRX now come with equal length exhausts, so not much rumble to speak of.
I don't know that your car would be any louder than any other 4 cylinder. You really want a muffler delete? My car with the 4 inch axleback is plenty loud. My VW-based sandrail had no muffler..but you know...it was a sandrail.