Got the remus quad conversion from Tag. Very happy with the work. We talked about installing M5 diffuser but with my comfort access sensor, they told me it looks like a few hours work and would run me a bit more $ than I'd like to spend, so ended up getting 550 M sport diffuser. Sound is not loud at all but sporty. no drones.
I definitely recommend Tag Motorsports. Sean worked with me and they are legit.