Start by removing the two...
Start by removing the two bolts from the flange that connects the muffler and the tailpipe.
One of the first things that people do when they pull their new truck off the lot is gloat to their friends. After that, they usually grab one or two of the easiest performance upgrades on the market, such as an intake or an exhaust. These basic upgrades unlock horsepower that are just waiting to be released as your ride rolls off the production line. It shouldn't be that much of a surprise that we wanted to do the same thing with our Nissan Titan project truck.
Originally, we had planned on doing headers and a full after-cat system, but when the Nissan engineers designed the exhaust system on the Titan, they decided that the best placement for the cat was literally right on the exhaust manifold. The design makes it a little difficult for manufacturers such as Gibson to create smog-legal headers without altering the position of the cat. Hopefully, in the future, we'll see a header solution that will still get past the smog nazis, but until then, we'll just rock out with our Gibson pipe.
The Gibson after-cat single exhaust is the epitome of easy performance, unlocking 12 hp and 13 lb-ft from the 5.6L powerplant as well as a few mpg, all in less than an hour. Follow along as Shawn helps us swap out our factory pipes for Gibson's 3-inch heavy-duty stainless-steel exhaust.
 Start by removing the two...  Start by removing the two bolts from the flange that connects the muffler and the tailpipe. |  A few squirts of WD-40 will...  A few squirts of WD-40 will ensure that the hangers for the tailpipe and muffler slide out of the rubber grommets easily. |  Next, unbolt the factory Y-pipe...  Next, unbolt the factory Y-pipe from the flanges. Make sure to remove the ground on the driver-side flange, and keep the factory gaskets because they'll be reused later. |
 Since the factory hanger slides...  Since the factory hanger slides forward on the Y-pipe, it'll be easier to just unbolt the rubber grommet from the frame and drop the pipe down. |  Once the Y-pipe is disconnected,...  Once the Y-pipe is disconnected, it can be completely removed from beneath the truck. |  The new Gibson Y-pipe will...  The new Gibson Y-pipe will line up with the flanges on both sides. Bolt the pipe on and don't forget to reconnect the ground on the driver side. |
 Slide the rubber grommet onto...  Slide the rubber grommet onto the Gibson hanger and bolt it back to the frame. |  The resonator and the Superflow...  The resonator and the Superflow muffler will both slide into place after the Y-pipe. |  Secure the muffler using the...  Secure the muffler using the band clamp, but make sure not to tighten any clamps until the entire exhaust is hung and set properly. |
 Slide the tailpipe over the...  Slide the tailpipe over the axle and connect it to the muffler. This will be your chance to position the exhaust exactly how you want it to hang. |  Next, secure each side of...  Next, secure each side of the muffler with the provided 3-inch clamps. |  Finally, slip on the stainless...  Finally, slip on the stainless tip and then begin tightening the entire exhaust system, working your way from the front to the back. |
 The dyno run shows an increase...  The dyno run shows an increase of 12 hp and 13 lb-ft at 4,900 rpm, which isn't bad for less than an hour's worth of work. | | |