Lou,
Here's an interesting track map of VIR, made by a friend who races an Aprilia RS250:
<img src="http://home.nc.rr.com/jeffspics/VIR%20race%20lines%20and%20shifting.gif" style="border:0;"/>
I run 16/44 gearing and am just about 1 gear higher than his track notes at every corner, mostly because the Mille has about 75+ ft-lbs of torque to drive you off every corner.
If you're running 15/43, I think you might run out of gear in some spots. My most recent trip there I was short shifting into 6th before the finish line kink and hitting 158 mph (Vmax recording) braking at the 5 marker before turn 1 with about 800 revs left in top gear. I go down 3 gears and take turns 1-2 in 3rd.
I had trouble coming out of turn 2 going to three as I shift up to 4th in the slight kink and hit the limiter before rolling off to turn into 3. I hold 3rd through the tight 4-5 chicane and through the exit of the snake.
I also would hit the limiter in 4th coming under the bridge approaching the braking zone for turn 7 "Uphill". I think if I had 16/43 gearing it would help out and maybe cut a 1/2 second from the lap by allowing the bike to keep accelerating before turns 3 and 7 before instead of touching the limiter and losing drive.
They widened the exit of 7 (top of the hill) for the cages but you want to keep it tight to the outside curb at 8 shfting into 4th to get a good entrance to 10 (flat->negative camber where Nicky crashed last year in the final AMA race). This is one of my favorite parts of the track as 11 falls away and you're pinned in 4th gear, straighten the bike up through 11 and it wheelies just by the left curb of 12 before you shut it down and back down a gear for the "Roller Coaster".
I hold 3rd through the tight right of 14, but I suppose you could go to second if you're really trying to get on it. It drops off so steeply for the right flick that I still get a little wheelie in 3rd sometimes when hard on the gas.
I really hang off the bike to keep it stood up on the fast part of the tire accelerating down the hill towards 16. This is a very deceptive turn because you can really carry a lot of speed into it. It's got a blind entrance with a steep drop-off afterwards that's scary (Mladin lost it here and the bike caught fire at last year's AMA race), but once you get used to it you can make a load of time on other bikes. Just be ready to flick hard to the right and hold a tight line through 17 and 17a - I usually pick up my knee to avoid the right curb flicking right after 16.
17 and 17a are super fun as you take it as one turn, and exit at about 110-115 mph, knee firmly on the deck. My shift points with 16/44 gearing match the chart above from 17a through the front kink.
I was running SuperCorsa SC2's front and rear last time and my XT lap timer showed me doing consistent 1:40 flat, which is about 1.5 seconds faster than the CCS Amateur Heavyweight Twins race last year. I might just do a one-off race at the next CCS meeting to show the Championship winning Ducati that he better be glad that a certain Aprilia isn't challenging him at every circuit!
If you haven't already, download the on-board video of the North Course from Aaron Stevenson's Cornerspeed school website: <a href="http://www.cornerspeed.net/photos.html" target="top">Cornerspeed School on-bike videos</a>
I wish I could be there for The Great Duc Hunt, enjoy it for me and post the pictures!
Best regards,
Jeffrey