Getting Super Powers

Yellow Performance Parts
These engines are all about delivering the middle of the road power output. Think of this as a Ram Air Intake upgrade, which increases engine power in the lower-mid range. It's usually muscle cars such as a Dodge Viper SRT10 or its full-size relative, the Dodge Charger SRT8, that benefit from this engine, but it will also work for exotic cars like the Ford GT and the SLR McLaren.
Amerikon SpeedSystems
Quartz Speed Packages
Blue Performance Parts
These engines are high-torque powerplant designed to pack quite a punch, allowing for quicker acceleration. What this would be suitable for is a low-RPM car, i.e. many of the classic muscle cars in the game (Chevelle SS especially), or in a real-life application, a high-torque AMG Mercedes.
Zero Tuning Mods
Stick Motorsport
Red Performance Parts
These engines are considered to be the worst brand for power parts according to the NFSW community, is the lighter version of AmerikonSS/Gromlen/Medion. The difference between the two is that this is NOT designed for V10 engines; rather they're more Inline oriented (Supra, Lancer Evolution and others of this nature). This is a must for every turbocharged engine, as too much horsepower will kill the car's torque, and too much torque will hold it back from its true potential.
Attack Motorsport
Green Performance Parts
These engines are tuned to provide high end hp with pretty bad low end torque, requiring an induction 9 times out of 10 to help out. Do note that this should be used only on cars with the peak near the high range (Nissan Skyline GT-R), rather than cars that still have quite a ways to go between their peak power and redline (Mazda RX-7).
Omnia Racegruppe
URSA Motorsport
Dynamo Aftermarket Kits