I just put a set in my AlphaRex Pro Series G2 and loving them. One of the reasons I went with them was I found a few reviews that gave the Kalvin number and these were are just below 5500. one of the lower values for LED. I find 5000 to be the closest to true white with less blue/purple. Most are at 6000+.
They fit on the tight space of the low beam and will easily fit in the high beam.
One thing I have found interesting is Headlight revolution and The Retrofit Source are in bed together, I have read other users thing GTR Lighting and Headlight revolution are in bed together. Well when I got my tracking number for the GTR Ultra 2 Series bulbs they are shipped from RetroFit Source. So RetroFit source apparently makes them.
I always knew that the Morimoto 2 Stroke LED bulb was the design that GTR copied, at least the cooling side. GTR was careful not to call there fan Mag Lev (like Morimoto) but to say bearing less instead. Now I know why.
difference between Morimoto 2 Stroke and GTR Ultra 2 not much from what I can see other than the supplier of the LED chip is a company that got sued for copyright infringment by Philips. As well as the GTR comes with lifetime warranty.