For SCCA, I think getting a tune takes you out of DS and puts you in DSP. However, I don't think anyone would know, or potentially care. The un-modded NA motor has a pretty decent torque curve for SOLO II.

Rule #1: Autocross compound tires. They come up to temp quick to generate superior grip. Hoosier A6's probably the best, but wear quickly and are the most expensive. Kuhmo's and Hankook's are both competitive, but don't offer a 19" option for the rear so you are left with Hoosiers or leaving DS by putting 18" wheels in the rear. Other Extreme Performance summer tires like Perelli Corsa System, Mich Pilot Sport and Yokohama AD08s are good, but you can't beat AX tires. MOST BANG FOR THE BUCK. I got 245's up front with a 1/4" spacer (legel) and 295's in the rear -- both on the OEM wheels.

Koni Sport Shocks (1228 -1229) have a good endorsement.

Folks have cut their springs, but that technically takes you out of Stock.

There is a front camber kit bolt that gets you another .3 - .5 degrees of additional negative camber which helps. I'm running -1.7. Check your rear camber. If you've lowered your car you will have to adjust your rear camber. If not, you still may want to adjust it. Mine was at -2.5 on one side, and I've settled at around -1.8.

I run about 1/4" toe out up front, and 1/2" toe in in the rear. I set the rear toe at home before I go to the track and adjust the front at the track while I'm changing the front tires. This makes the car really twitchy on the road, but makes the car respond very well on SOLO II courses. You don't want to leave the alignment this way for daily driving.

Do a throttle reset prior to the race. Really makes the car jump off the line.

Remove the junk from the trunk. Tape down the cup holder. Get a G-Lock seatbelt lock, or twist the belt before clipping (I installed the Roadster sport hoops and a 5-point racing harness -- really holds you in).

Use the search function here and see what Wedge, SOLOII Racer, Velociabstract, NOCones and Woody have posted. Lots of tips on setting up the car.

And now about the driver: Evolution Driving school. Get a wheel & pedal set up with FORZA or Gran Tourismo or iRacing and practice what you learned at Evo. There are also some good reads on how to drive.

Don't change too much all at once (ask Les about that one), and I would tighten the nut behind the wheel before you spend too much time and money on the car. Its pretty dang good without much changes.

Good Luck
Mike