Best way to add Horsepower to an 2003 Impala?

2003 Chevrolet Impala 3.8L:


I want to add some more horsepower to my car without putting in a turbo/super charger. I was thinking of putting in the K&N Cool Air intake which they say adds about 13HP to the car. I'd like to have a little more than that as HP helps when trying to manuveur around cars on the highway or when you have addtional people in the car, or even worse, extra people in the car and the A/C running.

What do you guys think of these?

http://www.stchiptuning.com/  (says it adds almost 22HP without using too much extra gas, how is this possible?)

or from the same company there is an electric supercharger:

http://www.electricchargers.com/ (Adds up to 30HP for $100 plus they send you a performance chip)



Also is it possible to replace the ECM/ECU to increase horsepower and not use more gas? I thought the only way to increase power was to send pressurized air into the combustion chamber (cold air heps too) in some way. Or use NOX.

you could try a cold air intake, which goes under your car and sucks in nice cold air..that gives a lot of power. The only thing is that I'm not sure if it fits on the impala

Custom FWI or Ubend delete...thats a good start