So I just installed Bilstein B6 with new OEM springs and 6mm spacers.  Overall lift is ~3/4".  I plan to do some track days this year and will report back.  I am slightly concerned about the higher CG.
Honestly, a stock suspension will do great in rallycross and plenty of people track their stock cars.  I would leave the suspension stock until you know which discipline you will be doing more of.