I've found the 991 xenons just average on low-beam but pretty damn great on high-beam, and I just noticed why today. When activating high-beams, the 991 uses both the halogen flash-to-pass beams and the full xenon beam (shutters open).

Also, flash-to-pass behaves differently depending on if your xenons are on or not. Flashing while xenons are off will just flash the halogens, which makes sense because xenons take a few seconds to reach full brightness. Flashing while the xenons are on will flash both the halogens and the xenons.

I found this interesting because it contrasts with my previous BMW, which used the halogens strictly for flashing and never used them in conjunction with the xenons...and I just love lighting technology in general.

 

Interesting! Yes, the tech on most new cars is amazing!