Was checking around the forums as to what others had to say bout their RS3 purchase when I came across some talk of the RS4...not many people using it and wondered why if it really can reduce the drone some complain of when the top is up. Anybody actually have/heard this muffler before and is it worth buying over the 3? I have to get this right the first time when I buy cuz the budget is limited (kid going to grad school next year).