I had a 997.2 GT3 for a while, now fantasizing getting a 991. A popular option I see on about half the cars I see is:

643 Sport Chrono Package (Porsche Track Precision App)

Can someone explain what this is and what it does and is it something important to have on track?

 

For 2014 it was just a clock. For 2015 on it includes the Track Precision Ap. The track Ap has mixed reviews. There are some threads on it if you search. I use AIM Solo.

 

For the 991.2's (2018+) the track precision app support is standard.

 

In 991.2, SC gets you the dash clock and also the wiring that allows you to connect the Porsche lap trigger.

 

I have no idea what it does, but for this kind of money why would anyone not spec it?

 

^^ LOL

 

I regret not speccing it.

 

so my hot secretary girl asks "whats that thing that looks like a clock on your car do?" I said "I dunno, all I know is it cost me $1800 dollars and looks cool"

 

.1s with Sport Chrono are wired for the lap trigger as well, but most who track just use a data logger w/GPS.