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2004 Nissan Titan Exhaust Upgrades - Project Mega Titan: Part 9

Posted in Project Vehicles on June 1, 2009
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Over the years, our Mega Titan has seen lots of hard use. From multiple trips over the Rubicon Trail, to Moab's infamous slickrock, to the extreme hardcore challenges of Johnson Valley, the rig simply gets its use. Through it all, the original exhaust we installed has remained unscathed. We installed the setup back in '06 during our mad dash for the rig's debut at the SEMA show in Las Vegas. Today those parts are working just like new. As such, we felt an in-depth report was in order to show off what gives our larger-than-life mega-project a sound to match. Check it out.

The factory exhaust manifolds on the Nissan Titan have a catalytic converter built right into them. This arrangement is very restrictive, so Stillen designed their replacement long-tube Titan headers to eliminate the factory cats, therefore freeing up horsepower. In doing so, Stillen was able to achieve gains between 25 to 30 rear-wheel horsepower. Stillen currently offers these stainless-steel parts for Nissan Titans and Armadas in a polished or ceramic-coated finish. Note: These headers are not approved for emissions-control vehicles.


The first step to installing the new Stillen headers is removal of the OE exhaust manifolds. To do so, we simply used a ratchet to break each of the header bolts loose. Then we used an impact gun to finish removing each of the nuts securing the manifold to the aluminum heads.

We took the opportunity to compare the flange thickness of the factory exhaust manifold to the new Stillen unit. We were impressed to find the Stillen flanges 0.06 inch thicker than the factory flanges. This increase in thickness should prevent the flanges from warping over time.

With the factory manifolds removed, we had a chance to apply Loctite 272 to the factory studs. This step isn't always necessary, but we felt better knowing the studs were secured soundly with a temperature-friendly fastener adhesive.

Lucky for us, the Mega Titan didn't have inner fender plastics to remove. Otherwise we would have spent a lot more time between the front wheelwells.

Here you can see the new Stillen header as it was about to be snugly attached to the Nissan Titan's cylinder heads. Note the factory studs accommodate the increased flange thickness without issue.

The parts shown here are designed to trick the Titan's ECU into thinking the catalytic converters are still present. Essentially, when you remove the catalytic converter, the O2 sensors read raw untreated exhaust and send a signal that trips a "check engine" light. So the folks at Stillen had to develop an electronic solution to the problem. Once these parts are wired in, each of the O2 sensors' output signals are "conditioned," bringing each output back into a tolerable range.

After the new Stillen headers were installed we installed a pair of Flowmaster limited-edition signature series Classic 2 Chamber mufflers. These "suitcase"-style mufflers are what made Flowmaster famous back in the day. They employ a series of angled interior baffles that create a recurrent scavenging effect on the combustion chamber. This improves exhaust flow while deadening engine noise only minimally. Flowmaster's founder, Ray Flugger, designed these new Classic Two Chamber mufflers as a re-creation of the square-cased muffler that started it all back in 1983. They imitate the looks of the original but incorporate a slightly wider case, a new Delta deflector with the old-style baffles, which produces an unmistakable sound similar to the original Flowmaster mufflers. We like them because together with Stillen's headers, we have an exhaust note quite unlike any other Titan in existence.


Costa Mesa, CA 92626

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