It depends on what your goals for the car are. Then you need to compare those goals with what the rules stipulate. For example, I have a 1992 Accord EX with an Eibach Pro-kit, KYB AGXs, a S/T rear sway bar, upgraded bushings on my 25 mm front bar, wagon front brakes, EBC Green brake pads, under bumper ram-air induction, upgraded stock-type ignition parts, 16" wheels (with "H" centercaps a la JDM wheels,) some mild cosmetics, and a forthcoming cat-back system. Theses mods deliver improved performance and looks, the car is totally streetable, and the car is suited for Street Prepared competition. Granted, there are a lot of things I could do do improve the performance on course, but as I have learned over the years of doing this, either drive a car that kicks ass in stock trim, or have another car that responds well to modifcations, needing only a few to do well. Accords are always going to be limited in their ability to perform because of some inherent issues. How much money, and to what lengths you are willing to go to to make the car perform at a competitive level is totally up to you. But I can assure you, even with a $2,000 brake system upgrade, stock class M3's will spank you. If I were you, I'd do the wagon brakes with good autocross pads, build the car to compete in F Street Prepared, and get seat time, and go to a few training schools, learn good habits from the beginning, and you'll beat people who spent a lot more on their cars than you.