Need some help on suspension modifications please.

[eicheldp]

I have a basically stock 2004 986 S with 31,000 miles and have been bitten by the autocross bug this year. One of the items I did change was I went to 17" wheels and summer performance tires, replacing the all season tires.

Some of the photos I've seen of my car on the track looks like I am experiencing body roll. Tell me if I'm wrong.

I would like to stiffen the car more but I also want to keep the car for street use as well. What would be some suggestions for improvement. I was thinking of a rear stabilizer or maybe a front stabilizer that mounts in the frunk.

Please let me know your thoughts.