There is no surefire answer when it comes to increasing the power output of your 4A-GE engine. However, there are a number of modifications and upgrades you can make that will result in more power. Some common ways to increase power on a 4A-GE include:
1) Upgrading the intake and exhaust system - A better flowing intake and exhaust system will allow the engine to breathe easier and make more power.
2) Installing larger valves - Larger valves will also help the engine to breathe better and produce more power.
3) Porting and polishing the cylinder head - This process involves opening up the ports and smoothing out any imperfections in order to improve airflow through the head. This can lead to a significant increase in power.
4) Increasing compression ratio - A higher compression ratio will enable the engine to make more power, but will also require premium fuel.
5) Adding forced induction - Turbocharging or supercharging your 4A-GE will give it a big boost in power. However, this is a more advanced modification that should only be attempted by those with experience.