Best Performance Upgrades for Little Money - Here's My Vote

The two greatest speed tricks for me?
1. A good performance ignition curve - will work on a Race Hemi or 170" slant with any parts they have. Cost might be as high as $25 if you have to buy beer for the guy with the welder.
2. Make sure your tire pressures are close to the max noted on the tires especially on the front. Also has a side benefit of getting better gas mileage and again - works on everything from a lawn tractor to a fuel rail. Cost is free at most service stations.