Free flow air filter- always go for the biggest element you can, itll have less restriction than a smaller one.
Get it tuned up, its also possible to gain a little extra here and there by optimising the cam timing.
Ensure the plugs are the right ones and correctly gapped.
Ignition system in the best possible condition and timed correctly will pay off in terms of power and economy.
After that youre into machinework and wallet pain.
