[Jeph]

I'm guessing your times would be very close to a stock Tiptronic S. Of course things like temperature, altitude, and humidity may effect your numbers -more so than your tire pressure I'd presume.

Since a Tiptronic is merely an automatic transmission that you can shift manually, I wouldn't expect putting it in manual shift mode would help at all. In fact, I would place my bet on it being slower.

I'm not certain, but I feel pretty comfortable in saying stepping on your brakes while revving to 3k is not good for a Tiptronic. I would advise against it. It sounds like you're thinking of launch control, which is commonplace on other vehicles with proper SMG/DSG styled transmissions.

Times? I've never seen a Boxster on a 1/4 mile strip.