A lighter driver? Seriously, shedding weight is the cheapest way. Lighter is faster. Remove everything you are willing to, without compromising performance or handling. All the airbags would shave some weight (you'll throw airbag codes, not a big deal, until you get simulators plugged in), the soundproofing under the carpet, the rear seat, trunk carpet and liner, engine cover, the stuff in the spare tire well, most of your gas, I'm sure there's more....