When I built my King back at 2005, I regretted it, a tiny bit, I didn't do elliptical routing in the turns, so I could of maybe held on to the World Records, for another six months, or so.
The thing I most regret, is not building the track with bigger aprons.
I thought about it long and hard, when I was building it, but I decided on what I went with, based on being able to still reach the innermost, lane, to marshal the cars.
The net result is, if you overcook your car, on Black, in the 90 , and / or the Donut, about a quarter of the way up, up the Donut, the back of your car will hit the wall, and if too hard, will knock it out.
Since I was going to put clear walls up anyway, in the rest of Donut, (I already had done part of the Donut, for improved visibility) to replace the well-worn vinyl soft walls, I decided to increase the Donut apron by laminating on 1/4" pieces of MDF, vertically, starting at the beginning of the Donut.
Anyway, with a little help from Howie, Ursaner, Michael Iga & Andy Fisher we finished it before the warm-up race, and it turned out real well.
Now you are able to go much deeper into the 90 and the Donut and not hit that wall.
It is possible to still go too fast and you will just come out later, but Black Lane lap times will be improved.
An example, in the FK12 wing race, Michael Iga's best overall lap time, 2 races ago, was 2.826, with a best, on Black, of 3.05.
This last race, after the mod, Michael's best overall time was an almost identical 2.830, but his best Black time, was over a .1 quicker, a 2.93.
It's 4 boards wide, or a full 1" wider, at the spot where the cars swings the widest. It reduces / tapers down, to 3, 2, and 1 board. It doesn't appear the tires ever really hit it, but I'll be adding some paint, after a birthday party , this Sunday afternoon.
While 4.35 is a nice hot lap, especially for a not quite fully Sano prepped track, the big news is the 4.4's on Black.
Not sure if someone like Willy, ever has ever hot-lapped that fast on Black, but the best race lap, I've spotted in the results, is a 4.53, from Willy, with very few other 4.5's (on Black).