Originally Posted by x2o

If your car is currently stock, you do not need a tune. If you plan on doing engine mods that is when you will need a tune. Generally, you can do intake or exhaust mods independently without needing a retune, but once you do both intake and exhaust you will need a tune.

My recommendation, get the mods you plan on doing done, then finish it with a dyno tune.

Biggest bolt ons for power are long tube cold air intakes and less restrictive exhaust. If you're in a place without emissions, the stock cat converters are the most restrictive piece of the system