A tune up will return the power level to factory specs. This would include plugs, wires (cap/rotor if equiped with a distributor), fuel filter, possibly a PCV valve.
To get more power out of a NA (normally aspirated) engine, you need more air getting into the engine. This would include higher lift/duration cams, larger throttle body, free up the exhaust etc.
Generally the cost is high for the benefit received.
Other options include nitrous oxide, turbo or supercharger. These are also expensive (except nitrous), but will increase power.
Having said that, remember you are significantly increasing cylinder pressures on an engine with 150,000 miles by using any of the 3 above.
The engine (fuel, ignition maps) must be changed when increasing power. A turbo/supercharger may require larger injectors, new/modified ECM. Nitrous may require larger fuel pump.
In any case, you would be risking reliability. Some models, Toyota Matrix, Pontiac Vibe offer a dealer installed supercharger.
You can get yourself into trouble increasing power on these small engines, not to mention money.
Thursday, June 28th, 2007 AT 6:20 AM