Quickie 500 was originally intended to be a entry level pylon racing class. The rules called for 500 square inches of wing area in a constant chord wing with a minimum thickness of around 12% of the chord. The engine must be totally exposed and have a side exhaust and throttle. (sport engine in other words) The fusilage must have a square cross section and there are probably a bunch more rules that I can't think of at the moment.
Some clubs have classes with further restrictions for example, having to use an engine that costs less than $100 dollars.

Anyway, there is a lot of built in by the rules drag in a Quicky 500. If you are not constrained by needing a plane that is legal for pylon racing, you might check out designs for electric hot-liners and convert to glow or build a state a of the art QM-40 plane ignoring the side exhaust and exposed muffler rule. Effective cowlings for engine cooling and in the fusilage mufflers go a long way in reducing drag.

Drag is the enemy of speed. When you are trying to go 200 mph, everything matters. Exposed control surface horns and linkage, landing gear, exposed radio switches, retractable landing gear that retracts into holes that stay open etc.