I think of it as modifying a vehicle to perform better than the original. In the context of PERFECT POWER, it means modifying the engine to perform better. In most applications it means getting more power out of an engine, but more motor enthusiasts demand fuel economy at cruising, and lots of power at full throttle.

Engine performance can be categorized further in to:

MILD & STREET LEGAL
You get up to 50% increase in power. The modification is not visible, and you drive on normal street tires. Other family members can drive the car. You are using this car regularly, and you may tow a caravan or boat trailer. You may beat the little imported sportster.

EXOTIC BUT STREET LEGAL
You get up to 100% power increase. The car looks modified, it has a new drive train, and wider tires. You don't lend the vehicle to younger family members. The exhaust noise wakes your neighbors. The police think you are a maniac, and no one races against you.

VIOLENT
It is a dragster, in one form or another. You modify the engine until it breaks. Then you fix it. Brutal power, and the noise to match it. No one wants to drive it, they are scared. The engine gets reconditioned every 15 minutes. The adrenaline rush from driving it can't be matched. Even looking at it gives you goose pimples. WHOA!

PROFESSIONAL
Indy or F1 cars. Mega bucks budgets. Nice race preparations. Fantastic performance. Most of the parts used you can't buy, and they won't tell you how it's done.

PRIVATEERS RACING & RALLYING
Modifications are possible within the rules of the racing class. The power increase is usually small, but economical to perform.

PERFECT POWER is involved in all of the above, and supports racing and factory teams.  It's fun!  Can you think of any better way to spend your time?