I recently had remote start installed on my 2017 Golf R and wanted to share my experience in case is anyone is looking for it; I know I was beforehand but I didn't find a "beginning-to-end" story. Just so you know it's a fairly long read, but if your serious about getting a remote start and don't know anything it might be worth it.
The two main manufacturers are Compustar and Viper, I found Compustar to be the most common of the two among the installers I called. The installer I felt had the best reputation and got the best "vibe" from didn't deal with Viper, so I went with Compustar. The other installers felt like the "Audio Express" calibre of shop, they didn't take the time to fully answer my questions, and it felt like they were in a hurry just to take my money.
In my situation I wanted to be able to cool the car before driving home - it's 110-115 in Phoenix right now in the afternoons. In a hot car it takes about 10 mins of full AC to get to a comfortable temp, and my drive home is 15-20 mins. Between where I park and my desk inside the building it's about 800 feet in a straight line, with just one exterior wall between me and the car. I was a little concerned about range claims so I decided on a 2 mile range system just to be safe.
The one I chose was the Compustar PRO 2WR3 (model RFX-P2WR3-SS). I'm not really looking to use Drone Mobile - I'm concerned about their database security - but it's now included "free" on most Compustar systems, and it came with this one. I might use the free trial at some point, but we'll see. I've read about their databases being hacked, and the usual horror stories about app stability. I didn't really want to be carrying 2 remotes either - you will still need the VW remote to unlock the car and drive - so this Compustar is the smallest one they make, about 2" x 1" x 3/8" thick. Using the phone app would eliminate the need to carry that remote, but I plan on starting the car from my desk and leaving the remote at work. You do not need the remote the enter the car and drive.
So the deal I got from the installer was $745 for
2 x RFX-P2WR3-SS 2-way remotes + Drone mobile module
CMVWXA0 iDatastart module for VW
ADS-THR-VW1 wiring harness for VW
installation labor and materials
On top of that you will need to give up a VW remote/transponder key. There is no valet key for this car, so you need a fully functioning remote that gets installed with the system. So (if you want to keep a second key as a spare) that was an additional $230 from the VW dealership. That was a story in itself.
A local locksmith said he could sell me a key and copy it from my other key for $250 (VW originally said $375). He did have some fancy looking copying equipment and appeared to know what he was doing, but ultimately failed to program the blank VW key, and wiped my original. He was able to restore the original and as I was about to leave I asked him if my second key would still work, he said no. So bummer, now I have only one working key! He was pissed too for having to spend an hour in 100F for no profit. He was able to reprogram the second key, so I was back where I started for $0 cost, less a couple of hours wasted time. Lessons learned - you can buy blank VW remote/keys for about $110 but they need to be programmed to the car - and the next part is important - all the keys need to be programmed at the same time, any key not programmed becomes "de-programmed". And the dealership seems to have under charged me (or over quoted me on the phone) - out the door with a new third key was $230. (Berge VW/Mazda, Mesa, AZ)
As far as how the system works, so far so good. Starts no problem from my desk, 10-15 minutes before I leave and the car is cool when I get in. Mission accomplished. Haven't tested the limits of the range yet. The installers programmed the engine run time for 25 mins; you can also choose 10 or 45 mins. I'm not sure I can change that myself, but the installer said they would do it if need. The remote LEDs and the car's lights give you a lot of notifications about what's going on; engine on, run time left, battery level etc. Too many to list here. The remote feels nice and small, but a quality feel to it.
So $975 all in. Pretty expensive I guess, but it was my 30th wedding anniversary present to myself. But you could save $230 or so if you're willing to live with one key - not I.
If you have any questions, I'm happy to answer. I've gotten a lot from the forums, and I'm glad to have an opportunity to share. Oh and the installer was Handcrafted Auto in Chandler, AZ. I can recommend them.