Diesel Part: NOS Diesel Nitrous System for the Cummins, Duramax, and Power Stroke engines
What It Is: The kit has a "dry"-style nitrous-injection nozzle, which sends nitrous oxide through the intake system, and more fuel is added through the injectors.
Why It's Cool: They say without upgrades to the fuel system, expect an extra 50 hp. With upgrades to the system or with a chip, it's possible to make 60 to 150 more horses.
Where to Get It: NOS Nitrous Oxide Systems, 800/HOLLEY-1 or 270/781-9741, www.nosnitrous.com
Diesel Part: 5-Inch Exhaust for '04 1/2-'05 Cummins engine
What It Is: Stainless steel mandrel-bent tubing from the downpipe clear to the 6-inch polished tip. Features a 7-inch-round by 24-inch straight-through muffler and OEM-style pre-welded stainless steel hangers.
Why It's Cool: The idea behind "straight-through" is for unrestricted flow to eliminate backpressure, up the fuel economy, and lower the EGT.
MSRP: Performance Exhaust, polished with tip, $990.57; XL Exhaust, unpolished and without tip, $790.63
Where to Get It: MagnaFlow, 949/858-5900, www.magnaflow.com
Diesel Part: 63-Series AirCharger Intake System for '04-'05 Duramax engine
What It Is: It's a free-flowing, custom-engineered intake tube for smooth airflow from the filter, and includes a high-flow air filter that's washable.
Why It's Cool: All but eliminates intake tract restriction to the engine, which means a bonus 12.5 hp, they note.
Where to Get It: K&N Engineering, 800/858-3333 or 951/826-4001 (tech), www.knfilters.com
Diesel Part: Intake System Combined with Ram Air Hood for the Duramax
What It Is: An intake and a fiberglass hood with a functional scoop, but the real magic happens when the hood is closed; it makes contact with the intake lid, seals itself to the hood scoop, and allows cold air to enter the filter box to improve performance.
Why It's Cool: A colder intake charge can make more power-and you get a hoodscoop too.
MSRP: For intake system with box, the LLY is $465, LB7 is $444; the scoop runs $187.50
Where to Get It: Volant Cold Air Intakes, 909/476-7225, www.volantperformance.com
Diesel Part: Digital Propane Injection System for Cummins, Duramax, and Power Stroke
What It Is: A closed-loop ECM constantly monitors engine parameters, such as propane vapor temperature, over-boost, and rpm. If the parameters are not met, no propane is added to the engine. The DPI system is programmed for each application, so there are no jets to drill or external adjustments to deal with.
Why It's Cool: When propane is injected into the turbocharged diesel engine, there's an increase in power and torque.
Where to Get It: MSD Ignition, 915/857-5200 or 915/855-7123 (tech), www.msdignition.com
Diesel Part: Activator Module for Duramax engines
What It Is: Reprograms the MAP and fuel sensor to add injection timing and fuel enrichments without raising the fuel-rail pressure past the factory limit of 28,000 psi.
Why It's Cool: It plugs into the wiring harness using OE-style connectors and can be adjusted from inside the cab.
Where to Get It: TS Performance, 270/746-9999, www.tsperformance.com
Diesel Part: Diesel Fuel Supplement
What It Is: It cleans up the fuel injectors for proper fuel flow by eliminating gum and resin buildup, and removes water from the fuel and other junk that can screw up the spray patterns.
Why It's Cool: As they say, cleaner burning power and efficiency equal a happy engine.
Where to Get It: Justice Brothers, 626/359-9174, www.justicebrothers.com