It's Easy To Overdrive Your Headlights In A Porsche
It's way too easy to overdrive your headlights in a car like a Porsche that is just such a pleasure to drive fast, especially at night for some reason. Maybe living in Central Oregon makes me more sensitive to that fact than those in more urban areas as we have a lot of critters roaming around at night. I don't know anyone who hasn't hit a deer, thankfully it's usually in an SUV or a truck as it can get pretty serious in a Porsche.
Avoiding Overdriving Your Headlights
It's simple math. If you're driving at night with H4 headlights you should probably think about keeping it at 68 mph or lower. That gives you a margin of 42' - you see an object at 350' and it takes you 308' to stop.
With LED's you can move safely at a bit less than 80 mph. At 80 mph you have a close margin of 11' - you see it at 450' and it takes you 439' to stop.
Bottom Line: It's not safe to drive over 70 mph at night with H4 halogen headlights.
Halogen H4 @ 70 mph - Safe? 2' to spare
JW Speaker 8700 LED @ 70 mph - Safe with 105' to spare: 455'