The 5 main elements of engine tuning:
1- Intake Parts
In order to increase intake efficiency, the most important thing is to remove anything that could become a restriction and guide air smoothly into the engine.
2- Exhaust Parts
The basics of exhaust tuning are in the increase of exhaust efficiency but it is not right to assume that the least resistance leads to the highest efficiency. By removing the muffler, exhaust resistance is radically reduced but engine torque is also reduces, adversely affecting launch and vehicle acceleration so it is necessary to have just the right amount of exhaust back pressure (resistance).
3- Forced Induction/NA Bigger= TBO
Raising boost pressure the engine is able to take in more air or feed more air for NA
4- Fuel Management
In order to burn fuel completely, it is necessary to have approximately 15g of air for every 1g of fuel (15:1) and this is called stoichiometric air fuel ratio. However, in practice an engines air fuel ratio tends to be richer in fuel than the stiochiometric ratio due to conditions like the atomisation of fuel (how well the fuel mixes with air) and the cooling effect that the fuel has on the engine.
5 - Ignition
The most popular option when tuning the ignition system is a change of spark plugs. Spark plugs have a heat range value and generally lower values (low heat range type) are appropriate for use in lower heat conditions, however in hotter conditions, the plugs can cause knocking (detonation). High heat range plugs work well at higher temperatures but can cause weaker ignition at lower temperatures and possibly misfire.