I have one of those in my MR2. Really nice gauge (and a good WB O2 sensor too). I created a custom gauge image set to look like my other Autopower Phantom series gauges in the car. Not sure how to imbed a facebook video, but here's a link to it on my motorsports page:
https://www.facebook.com/takubanmotorsports/videos
It's the video that looks like a gauge. haha. I don't think that style would work well in the FR-S/BRZ since it has more of a white background.
I don't know if it will sit right at that location since the clear plastic is angled. I agree that the speedo is pretty much useless since it gives the speed digitally by the tach. I have mine mounted in a center cubby-lid gauge pod location in my MR2. I don't see the same type of spot on this car. Maybe down by the AC controls or something? I mounted the controller for the gauge to a blank plate where things like the coin holder and stuff would go. That's in a spot close to the steering wheel and easily accessed. So I could see the same location for that piece on this car, but I don't know about the actual gauge.
What modules were you planning on hooking up to the PLX display?