RobRiguez, about a year ago I bought a unit that looked pretty much the same as the one on your link.
The first problem I had was where to mount it. I didn't want an ugly result and it wouldn't fit in the headlight and the cables didn't reach anywhere that suited.
The ignitor needs to send 80,000 volts to ignite the globe so cutting and extending the wire is a big no no due to increased resistance reducing the voltage.
I did it anyway, using the heaviest duty cable I could lay my hands on.
I attached the ignitor to the frame under the tank, just above the stockcoffin coveron the RHS (the coffin is not in use due to BAk install). The slim ballast I mounted in the coffin box.
This worked ok for a few weeks but then the ballast died.
I wasn't sure if this was due to the heat or the vibration or what so I got a new unit and lenthened the cable between ballast and ignitor, with fairly heavy duty cable as this carries 80 volts, and installed the slim ballast under the seat - under the ecu.
This too worked ok for a few weeks but then the ballast died again.
When I say it worked "ok", I mean that usually the lamp lit but not always. This meant that I had to check that the lamp had come on every time I started her up - PITA
I then went away from the ultra slim ballast and bought a normal sized one hoping this would be more robust. I installed it as per the second install, above, and it's been just brilliant for a year now, hasn't missed a beat.
The above is just my experience and a painful one it was. Hopefully this will help you avoid some of the same pain
Cheers