The biggest gains from hacked ECUs usually come in the form of added features like stutter boxes (for accurate and consistent drag launches), and re-tasking gauges to monitor other engine functions (to assist with tuning), raised rev limits (for the guys with seriously worked heads), and DATALOGGING(!). I'd rather be consistent than fast because driver error will get you sent home early in bracket racing unless the guy in the other lane makes an even bigger one. You can win bracket races with a 25 second car. Even if your competition is running 10's. Consistent passes are worth more than 30hp is, and ECU's can be tuned to help you with that.

I believe the 30hp reference in this thread is for a Turbo car. Yes, an ECU on a turbo car can yield insane gains in HP. The rules that apply to your Honda/Acura don't apply to turbo cars. Turbo Deisel engines can gain 80hp/280lbs of torque from an ECU getting re-mapped. Look up the BullyDog propane injection system. That company also sells chips for Deisel Dodge Cummins engines that produce insane gains and all you have to do is plug it in. Don't expect to ever pick up 30hp in a N/A car from a microchip, though.

I picked up 25hp on my GSX just by hacking parts off of it. "Free" mods. Of course that only works on de-tuned engines like the 4g63. I don't know how anyone ever feels a 1-3hp upgrade on a 100-125hp motor, or whether it's even worth discussing. All I have to say is my CAI on my civic looks great with the hood up. Sounds pretty cool too. As far as faster... eh? Faster than a what? Who am I trying to beat with this thing? Other civics?