I've had my Eventuri installed for about a month now and am very happy with it. I had one on my previous S54 car too. The induction and spooling note is night and day compared to stock. I can hear it clearly from inside even with windows up. That said, I've heard the MSR in person and I think it is a little bit louder from the outside. I suspect the Eventuri is a little louder from inside the cabin given the filter placement.
The performance gains on these intakes are all just about the same. What I like most about Eventuri is the design and build quality. The yellow-black CF weave is immaculate. I had the red-black CF weave on my last one and it was just as beautiful. The matching CF air scoops are a nice touch. The attention to detail is obvious--everything fits perfectly with clear instructions and extra fasteners.