The 35w setup is based on the industry standard and the original design for HIDs. It produces roughly 3000 lumens per headlight (about 3x your stock halogens) and in a complete kit would include a 5-year warranty as the estimated lifetime is about 5-7 years.
The 50w, in contrast, produces more light (perhaps about 20-25% more) but also more heat, so in smaller applications, some heat-related damage can occur. Because most bulbs are still designed for 35w, the 50w ballasts effectively "over power" the bulbs, making them appear slightly more yellow in color as compared to their true 35w color.
It's truly just a matter of whether you prefer reliability or the most light output possible. For most installs, I prefer 35w.
Between the standard 3Five and upgraded XB35, there are a few notable differences:
- The XB35 has a proprietary halide salt mixture that ensures higher luminosity, the highest degree of Kelvin (color) accuracy, and an OEM-like life span.
- The XB35 has a Philips-style metal base that ensures the bulb glass is kept at perfect alignment. The 3Five has our standard ceramic sleeve for alignment.
- In addition to the standard silicone cover on the wiring of the 3Five bulbs, the XB35 have a nylon mesh weave to ensure the best shielding.
For the civic you will want the HD Relay. The canbus is only for cars that have bulb out messages, typically only German cars.