Just curious, and obviously its totally course dependent, but how often do you guys have to shift down to first at an autocross event?

In my previous car (NB miata) I never shifted down to first. Only 3 or 4 times did the course call for shifts to 3rd and then downshifts back to 2nd. There were a few times when I would have cut a decent amount of time off if I downshifted to 1st, but for whatever reason the transmission would never allow me to do it (even with proper rev matching, and the transmission on that car did have a syncro on 1st...and reverse ) without really, really forcing it into gear. Since I am willing to leave a some time on the table rather than take my car home on a trailer, I just left it in 2nd and didn't worry about it.

With my Series II Rx8 being geared much lower than my miata I wouldn't be the least surprised if I feel the need to downshift to 1st for some slow sections - but I won't know till I actually get to drive the car.

 

1st and 2nd gear in the S2 is lower than the S1 so all else being equal you're probably better off not downshifting unless it's a pin turn

1st gear
S1 3.760 x 4.444 = 16.709
S2 3.815 x 4.777 = 18.224 9% lower

2nd gear
S1 2.269 x 4.444 = 10.083
S2 2.260 x 4.777 = 10.796 7% lower


usually the break point for down shifting to 1st in the RX8 relies on two things, getting below 3700 rpm in 2nd and the ability to make the down/up shift properly, you can practice seeing what you think makes the most sense for yourself by comparing the rpm/speed graphs between 2nd against 1st for your particular tire setup

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As Mark said, usually only at a pin turn.

One important thing to remember about first gear in an 8 is when to shift up to second in the first place. Some times there are several tight elements at the start and it's best to leave it in first until you clear it.

 

agreed. In my experience, if you do manage to get into 1st gear without shredding the gearbox at anything other than a hairpin, you will find yourself shifting back up to 2nd almost immediately ... you would end up losing a lot of time.