Diesel Part: Fullsize Truck Fan
What It Is: A fan for non-towing or light towing (6,000 pounds or less) diesel applications. It's a dual 15-inch fan that pulls up to 5,500 cubic feet per minute, eliminating the stock beltdriven fan and shroud.
Why It's Cool: Improving horsepower and gas mileage not enough for you? Fan noise is said to also reduce, while A/C output increases.
MSRP: $430 and up
Where to Get It: Flex-a-lite, 800/851-1510, www.flex-a-lite.com
Diesel Part: High-output fuel injectors for the '98 1/2-'02 Cummins engine
What It Is: Jammers, which are machined to feature eight orifices in the tips versus the stock seven, resulting in better atomization, faster fuel flow, and more precise spray angle. Five configurations are available, including the hard-core Stage 5, which can result in a 100hp increase.
Why It's Cool: The injectors are said to also be able to improve fuel economy by up to 1.5 mpg, depending on how heavy your right foot is.
MSRP: $800 to $1,100, based on application and level of performance
Where to Get It: Diesel Dynamics, 800/628-8111, www.dieseldynamics.com
Diesel Part: TruckMaster Torque Converter for Cummins, Duramax, and Power Stroke engines
What It Is: It's a tuned converter that lowers the stall speed to take further advantage of all the torque the engine produces. Has Torrington bearings, and furnace-brazed internals (versus spot-welds found in most factory converters).
Why It's Cool: It'll reduce transmission temperatures and increase low-end power and overall performance.
MSRP: Starts at $243, depending on application
Where to Get It: TCI Automotive, 662/224-8972, www.tciauto.com
Diesel Part: Exhaust for the '01-'05 Duramax
What It Is: A 4-inch-diameter stainless steel exhaust system that's considered after-cat, despite '01-'04 1/2 trucks not coming equipped with a catalytic converter other than in California. The '04 1/2 and '05 models do have a cat and the system will bolt right onto it.
Why It's Cool: It's got Reflective Sound Cancellation, which is about as self-explanatory as it could be ... but we'll explain anyway: It enhances the exhaust note but removes the cabin resonance.
MSRP: $899.99
Where to Get It: CORSA Performance, 800/486-0999, www.corsaperformance.com
Diesel Part: HOT Xcelerator for the Duramax engine
What It Is: Provides speedometer corrections, governor removals, and four levels of performance. In addition to increasing horsepower and torque, it's said to be able to read and clear trouble codes.
Why It's Cool: It will raise the rev limiter and remove the speed limiter, but it can be returned to stock settings. Better mpg is another perk.
MSRP: $979.79 for LB7, $879.79 for LLY
Where to Get It: Pacific Performance Engineering, 714/985-4825, www.pacificp.com
Diesel Part: Powerflow Exhaust System
What It Is: It's precision-bent on mandrel benders, and the brackets are zinc-plated. The system features a polished stainless steel tip.
Why It's Cool: Turbo-back, stack kits, and side pipes (the latter coming soon).
MSRP: $465 for the 4-inch diameter, $545 for the 5-inch
Where to Get It: Grand Rock, 800/321-3674 or 440/639-2000, www.grpipes.com
Diesel Part: Boost Cooler water/methanol injection system
What It Is: It adds 50-100 hp and cooler EGTs by injecting vaporized water/methanol into the combustion chamber.
Why It's Cool: Uses inexpensive off-the-shelf windshield washer fluid to gain horsepower and torque.
MSRP: $400-$500
Where to Get It: Snow Performance 719/271-5644, www.snowperformance.com