Go with AEM's cold air intake. As mentioned, you'll see the greatest gains since it's sucking cooler/denser air from outside of the hot engine compartment. Go with the V2 version of AEM's product if available for your car. AEM's V2 CAI version uses a resonance tuning feature that produces a very mild supercharging effect...basically the same 'Variable Volume Induction' (aka VVI) concept employed in cars like the ACURA NSX, TL, MDX, & RL. VVI is the induction counterpart to how tuned headers work with exhaust systems...resonance tuning.A couple-three other things...I would not expect to see more than 3-4 added HP from CAI in a '93 DX engine. Best results will be had if you also add performance exhaust...either axle-back or cat-back system will free-up added power, helping your engine to breath & flow more efficiently...you'll also see slight gains in fuel economy, but at expense of added noise.The AEM CAI offers a special accessory valve for their CAI systems that protects your engine from water induced lock should you enter a very deep puddle. This issue rarely becomes a problem unless you plan on driving in deep water.