Hummer H3 Alpha MagnaFlow Exhaust - Four Wheeler Magazine

We've been quite happy with the power output of our Alpha's 5.3L V-8. This 300hp, 320-lb-ft engine has proven itself to be very well matched to the 4,854-pound H3. From daily commuting to towing trailers to powering over hilly trails, we've never wished for more power. But hey, we're always game for more, and that's why we bolted on a MagnaFlow Performance Exhaust after-cat system.

This stainless steel system, new for the H3 Alpha, increases the diameter of most of the exhaust tubing by 1/2 inch; offers a more consistent tubing diameter and less bends than the OEM exhaust; and features a dual split-rear exit design as opposed to the single exhaust tip of the stock system. Further, the MagnaFlow resonator and muffler are freer-flowing than the stock units they replace. Both units have a stainless steel perforated core, and the muffler has stainless steel wool-an acoustical absorbent material that has high heat resistance. There are no baffles, chambers, or louvers to impede flow.

Matt Dinelli at Attitude Performance installed our new MagnaFlow system quickly and it went together with no glitches. Here are the highlights of this simple, quick install.

The kit includes a new inlet pipe, resonator assembly, mid-pipe assembly, and muffler assembly, as well as four clamps.
The kit includes a new inlet pipe, resonator assembly, mid-pipe assembly, and muffler asse
Removal of the factory system was pretty easy, though we did have to cut the stock inlet pipe in front of the resonator. This allowed us to remove the system in two pieces.
Removal of the factory system was pretty easy, though we did have to cut the stock inlet p
After we made the cut, the system was easily removed from the vehicle. When removing the stock system it's important to save the OEM flange fasteners and all rubber insulators as they will be reused to mount the new system.
After we made the cut, the system was easily removed from the vehicle. When removing the s

Installation of the new system begins at the front of the truck by installing the new inlet pipe to the driver-side catalytic converter at the factory attachment point using a 2.5-inch clamp. As is the rule with all new exhaust installs, we left all clamps loose so the system could be adjusted once it's completely installed.
Installation of the new system begins at the front of the truck by installing the new inle
The resonator assembly goes in next. It installs at the flange location using the two OEM bolts (we used new bolts and lock nuts) and into the new inlet pipe using a 2.5-inch clamp. This assembly includes a welded hanger that inserts into the OEM location using an OEM rubber insulator.
The resonator assembly goes in next. It installs at the flange location using the two OEM
Next up, the mid-pipe assembly is installed to the resonator assembly using a 3-inch clamp. This piece also has a welded hanger that utilizes an OEM rubber insulator.
Next up, the mid-pipe assembly is installed to the resonator assembly using a 3-inch clamp

The MagnaFlow system comes with dual 3.5-inch welded-on chrome exhaust tips. Naturally, these didn't jibe with our chrome-free H3, so we sent the muffler assembly out to LO-KO Performance Coatings in Oak Lawn, Illinois, to have the tips powdercoated satin black. If you dig the look you can have it done, or rumor has it MagnaFlow is considering offering black exhaust tips on some of its exhaust systems.
The MagnaFlow system comes with dual 3.5-inch welded-on chrome exhaust tips. Naturally, th
The last component to be installed is the muffler assembly. It is installed to the mid-pipe assembly with a 3-inch clamp and it utilizes three welded hangers that slip into OEM mounts with OEM rubber insulators.
The last component to be installed is the muffler assembly. It is installed to the mid-pip
With all of the components installed, Dinelli then went back and made sure there was ample clearance between the new exhaust system and the H3's frame and bodywork. MagnaFlow recommends at least 1/2 inch of clearance between the exhaust system and any body panels to prevent heat-related body damage or fire. With everything in order, he tightened up all of the fasteners beginning at the front of the vehicle. The band clamps need to be torqued very tight (approximately 65 lb-ft) to properly align the pipes and prevent leaks. Here you can see the resonator pipe connections at the flange and inlet pipe after tightening.
With all of the components installed, Dinelli then went back and made sure there was ample

Bottom Line
The MagnaFlow system for the H3 Alpha has an MSRP of $733.66, which is in line with the pricing of other systems. We're impressed by the overall quality of the MagnaFlow system, and it's so well-built, it's a shame it's hidden under the truck. When we left Attitude Performance after the install, we were towing a 5x10 trailer loaded with the H3's factory wheels and tires, the stock exhaust, and other odds and ends. We could feel a power difference. The engine felt more responsive. No scientific data to trot out, just seat-of-the-pants feel. Around town at low speeds the system generates a nice exhaust burble that you can hear in the cabin. At highway speed the new system is audibly transparent. We haven't had the system installed long enough to generate hard numbers, but we're interested to see if fuel mileage numbers increase slightly due to the freer-flowing system. Overall, we're happy with the results so far.

SOURCES
Attitude Performance 8-47/-593-0505 www.attitudeperformance.com	MagnaFlow Performance Exhaust 22961 Arroyo Vista Rancho Santa Margarita CA 92688 800-824-8664 www.magnaflow.com
LO-KO Performance Coatings Incorporated