That video was shot on "The Snake" which is part of Mulholland highway between the Rock Store and Kanan Rd. in the Santa Monica mountains. I've seen that guy before. The bike is a Sportster and to my eyes, looks to be fitted with longer rear shocks. I don't know about engine mods, but additional power would not make much difference on that road, really no place to use it. That rider is a Unicorn and is the main reason I used the word "some" when describing Harley riders. My first encounter with him was when I saw him turn onto the same stretch of canyon as me, a few hundred yards ahead. I was initially disappointed because I thought I was going to have to pass him and there was nothing but twisties ahead and I won't pass on a public road unless the rider moves over and waves me by, something Harley rider rarely do, or there's a legal passing lane. I figured I'd get in a few good turns and then park behind him the rest of the way. To my surprise, after a few turns he was still out of view (can't see very far ahead on this road). More turns, still no sign of him! I started looking over the edges thinking he'd maybe run off. There are no intersecting roads on this stretch either. Anyway, I figured it wasn't my problem and decided to turn it up a little. After a few miles I started to catch glimpses of him a few turns ahead here and there and decided to see if I could catch him. I ran it up to about 80% and only managed to close down about one turn before he pulled off a the Rock Store, same place I was headed. I was mightily impressed with his riding speed, maybe not so impressed with his judgement though.