I have a type S on my MR2 Turbo.
I ran it open for awhile and it was MEAN and NICE sounding, but I have to recirculate it or my car runs like crap, so I recirculated it, it still sounds WAY louder than stock and it works great.
Do yourself a favor if you get a Type S, (not sure about the RS) there are 2 nipples on it. A bigger one and a smaller one. The bigger one takes a vacuum source (like as in the one that feeds the stock valve). The smaller one takes a source of boost from the turbo to the wastegate (so you Tee into the turbo to wastegate feed line and send one side to the wastegate and one side to the turbo).
Before I did that it worked but it wasnt as responsive as Id hae liked. After I did that, it was much more responsive and had a better tone to it.