Lee, start with wheels and tyres, you did not mention which wheels you had, but I beleive the hoosiers will be quite heavy. I have custom made 13" three peice wheels and Avon ACB 10 tyres, and with the tyre fitted they weigh around 21Lbs each. Avon also do some very soft compounds which are ideal for autocross, I assume you are in a modified class, and tyre choice is free.
Lighter and more powerfull brakes are available, I saved 4.5 Lbs on the fronts, and got big stopping power (good for autocross)Hi spec 280MM discs, aluminium bells and lightweight four pot calipers.
There are some things you could just junk altogether, like windsheild (heavy), and fit the R500 screen. Don't know what seats come in the superlight, but if they are the standard leather ones they are also quite heavy.
Other things, lighter battery, smaller, lighter altenator, light flywheel and clutch.
There have been many threads on this subject with much better advice than I can give you, so it would definetly pay to do a search.