Stages, of tuning (stage 1, stage 2, etc)

There is no exact definition to what exactly constitutes a "stage" but here are some guidelines:

Stage1:

• free flow air filter (K&N, Piper, etc)

• better inlet manifold

• LCB exhaust manifold

• free-flow exhaust system

• uprated needle to cope with other changes

End result can be about 12% more torque and 20% more power. Definitely the best small-tune you can do, and the best value-for-money tuning upgrade.

Stage2:

• Stage 1

• modified head, usually I think enlarged ports/chambers

Stage3:

• Stage 2

• modified head with larger inlet OR exhaust valves

Stage4:

• Stage 3

• modified head with larger inlet AND exhaust valves

Stage5:

• Stage 4

• Extra, special head mods. Slanted guides, etc.

There is of course a lot of play with various cams independently of the "stage" upgrades.