Twin Cam Stage 1 Kit Install
I agree, you will not need to retune.....
FWIW...
The engine is an air pump... as air is pumped through the engine, the tune decides how much fuel is added for proper combustion.
The airflow is controlled (restricted) by the air cleaner, intake manifold, heads, pistons, and exhaust.... In OEM builds, the main restrictions to airflow (usually due to EPA noise standards) are the air cleaner and the exhaust.
If you change just the exhaust, OR the air cleaner, the engine will pump about the same amount of air, due to one of the two biggest air restrictions still being on the engine.
If you change BOTH the air cleaner AND exhaust, most OEM engines will then pump more air... Obviously, heads, pistons, intake manifold changes would be next, and increase the engine's air pumping volume even more...
More air through the engine = engine can be fed more fuel, thus making more power.....
The debate over when a tune is needed, is often contested andis it's own thread..... I won't comment on that here...
But sufice to say that even an OEM engine, with OEM components could benefit from a new (non EPA) tune....












