Spacers OK for track and autocross?

[heymanwatchthis]

I am considering adding some spacers to my '01 986S mainly to improve the stance.

I want to make sure spacers do not cause a problem with performance driving - I track a few times a year and run autocross. This is a concern for me as I was at an autocross race - a guy put spacers on his new Mini Cooper Works - a wheel came off during race! Turns out he did not use longer studs...as you could imagine it was an eye-opening experience!

I have been doing a lot of reading about spacers and have not been able to see definitively - I ask people, including techs, and they are not definitive, just not to 'go too big'. Is it a bad idea to track or autocross with spacers?

My wheels are 18" Turbo Twists, considering 7mm front and 14mm back. Could go smaller if it is more practical - i.e. 5mm front and 7mm back.

I think Boxsters look great with improved stance, however do not want to degrade performance.

Any of you running 7mm front/14mm rear spacers on track and autocross?

Thanks! Gary