Mine were easy to install, but since I have the dual headlights from the JDM spec Primeras I didnt need to do any re-wiring as you would with the stock headlights on the G20's
Installing an H4 HID kit is a little more complex since I think you must install a new relay and wiring from it. (I'm about 90% sure its the H4 kits that need the relays and wiring).
Still, it's not a very hard job. If you're unsure of yourself, just bring it somewhere to get it installed. You should only be charged about an hour of labor to do the job.
PrimeraGT (Henry) just installed some in his car, on stock headlights so he may have better input on the job.
One thing to remember, unless you get the Bellof H4 HID kit ($1200) you will lose the ability of having a high beam.. All other HID H4 kits are low beam only..
