Bully Dog 5-Inch Rapid Flow Exhaust Peak Horsepower: 355.09 Peak Horsepower: 551.87 Features: When Bully Dog Technologies engineers their Rapid Flow Exhaust Systems, they use minimal degree angles on their mandrel-bent piping. Smoother and fewer bends makes for better flowing and lower backpressures, moving air more freely to increase power while reducing exhaust gas temperatures at the same time. Available in 16-gauge aluminized T-304 micro shine stainless steel or T-409 stainless steel and diameters ranging from 4 to 6 inches, we opted for the 5-inch T-409 system with an optional 5- to 6-inch chrome tip with rolled ends. Tools Used: Sawzall, Ratchet, Extensions, 9/16 socket Installation Time: 90 Minutes Installation Notes: Since the Bully Dog Rapid Flow Exhaust System we ordered retained the factory down pipe, removal of the stock exhaust required cutting at the front of the system. We opted for the 5-inch exhaust system, which has noticeably larger tubing than the factory and other 4-inch systems. Because the pipe size is so much larger it took careful alignment and some trial and error before the system was clear from hitting any body pieces. That's why it's important not to tighten down any clamps until everything has been aligned properly and there is sufficient clearance. Impressions: Admittedly, we weren't sure how the LBZ was going to like the large 5-inch exhaust. Bully Dog recommends 4-inch systems for horsepower less than 450, 5-inch between 450 to 550 hp and their new 6-inch system for applications above 550 hp. Thinking ahead, we went the 5-inch route and were able to pick up a hair over 12 hp at 2,850 rpm and on average around 20 ft-lb from 2,800 to 2,900 rpm. Even better was that we didn't lose any power anywhere in the powerband. We mention that because one of the arguments of going overboard on the exhaust size is a loss in low-end torque. According to our testing, that wasn't the case in this scenario. Outside of hard power numbers, the Rapid Flow exhaust emits an awesome sound that lets everyone within earshot know that the Duramax isn't stock. We also noticed the lack of a loud droning in the cabin that can be produced by some aftermarket exhaust systems.

A side-by-side comparison of the pipe size shows how dramatically larger the 5-inch Bully Dog system is as opposed to stock Sitting next to the stock muffler, the Bully Dog piece doesn't look much different. But the straight-through design and increased diameter offers more flow and lower EGTs. With the Rapid Flow Exhuast System we were able to pick up a hair over 12 hp at 2,850 rpm and on average around 20 ft-lb from 2,800 to 2,900 rpm.

 Project Ronix Rig Sourcebox:

K&N Engineering
(800) 858-3333
www.knfilters.com
Products: FIPK AirCharger Intake

Bully Dog Technologies
(888) 367-9922
www.bullydog.com
Products: Rapid Flow 5-Inch Exhaust, Triple Dog Power Pup Downloader

Cognito Motorsports
(866) 426-4648
www.cognitomotorsports.com
Products: GM Eight-Lug 7-9 Inch Lift, Tubular Upper Control Arms, Dual Shock Hoop Kit

King Off-Road Racing Shocks
(714) 530-8701
www.kingshocks.com
Products: Pre-Runner Billet Piggyback Reservoir 2.5 Shocks

American Racing Equipment
(310) 635-7806
www.americanracing.com
Products: Chamber Chrome 18x9.5 Wheels

Cooper Tire & Rubber Co.
(419) 423-1321
www.coopertire.com
Products: Discoverer STT 35x12.5x18 Tires

SnugTop
(562) 432-5454
www.snugtop.com
Products: XTRA Vision Cap

Bushwacker Inc.
(800) 234-8920
www.bushwacker.com
Products: Pocket-Style Fender Flares

Shocker Motorsports
(661) 588-7702
www.shocker-inc.com
Products: Quick-Release Clear Mudflaps, Lift Kit Installation