I'm considering mounting a radar detector in my RX at the top of the winshield next to the rear view mirror (connecting power through the roof rather than having wires dangling down). Does anyone know if the dotted tinting (not sure if it's tinting or something else) near the mirror will affect the radar at all?

 

The dotted tinting will not affect radar. However, you could temporarily mount it to the windshield at that location and see for yourself.

 

i wonder if you ever succesfuly installed the Radar and how dificult the wiring was at that location?

 

First, for better performance, radar detectors should be mounted at the top of the windshield, which should be obvious, but apparently is not judging from the number of detectors I see practically sitting on the dash. Perhaps it's the wires causing the problem.
I have both of my cars wired for the V1 up at the visor on the right side, with the windshield bracket near the center, just under or to the right of the mirror.
My recollection for the RX was that I could not find a switched wire up in the center light module, which was a disappointment. So I ran the wire around the right side of the windshield, through the glove box opening and down to the cigarette lighter, which is a switched device, with a nice big fuse. This was a lot easier than it sounds, and I spent less time doing this than I did testing all the wires up in the light module.
If you search here you can find instructions for taking off the trim pieces to get to the lighter cord, where you can tap into the power line. The cord is totally hidden, and the plug can be tucked behind the visor when not in use. Putting the V1 into its bracket and plugging in the cord takes 15 seconds, and even when in use is hard to see.
For the premium installation, run wires for the remote readout module over to the left, and mount it on the far left of the dash, where you can see the arrows more easily than looking up and to the right; this is great for road trips.
Highly recommended.

 

^ +1 what tfischer said.

 

I did have the installation done. It was a V1 and I installed it at the top of the windshield, just left of the rear view mirror. It sits behind the dotted tinting. I actually brought it to a professional a/v car installer. Took the guy about 1 hour to hard wire into the ceiling. To be honest, I don't know where the wire goes from there, but he said it was a very straight-forward and easy job.

I asked him if the tinting would affect performance, and he said you could find people who said it would and people who said it wouldn't. He said he did not believe it affected performance at all, and on his car he had it behind the tinting. For what's it's worth, it works just fine for me.

The guy did point out to me that for true protection, you really need to supplement the V1 with a laser diffuser, but that installation is much more involved than I want to do right now...