Sunday, February 21, 2010

Nissan Frontier - Exhaust "Y" Pipe Mod

The first steps in modifying a car for performance often lie in the intake and exhaust systems. My 06 Nissan Frontier Truck is no different. However with 265 stock horse power, I did not find a need to gain more power. Last fall however I was out four wheeling and got the truck stuck on a large rock. The truck was dragged over the rock, and in the process a section of exhaust pipe was crushed. The decrease in exhaust pipe diameter was not very bad so I did not do anything about it. However after many hundreds of miles of driving it, I did notice that things were a little off. The idle was rougher, the MPGs took a slight hit, but the main thing that got my attention was the smell of rotting eggs after a hard pull. Since the crushed section of exhaust was on one bank of the V6, I suspected that those three cylinders were running richer the other three. This was made worse with my air intake modification. More available air would mean more gas into the system; and if one side was not running as efficiently as the other, excess unburnt gas was being pushed into the catalytic converter: the most common reason for the rotten eggs smell. Not counting hotsprings and skinky roommates.

My truck is V6 with a single exhaust. This means that somewhere in the system the exhaust pipes from the two separate engine banks need to be combined. This truck does so with a "Y" pipe. The factory Y pipe is constructed by crimping two circular exhaust tubes into a half circle and jamming them into a third pipe. The result is a very restrictive junction. As we know the more free flowing the exhaust system the better the engine runs. Lets not start an argument about back pressure now. This is an excellent place for a little performance modification. As some of you know I, like many other people, suffer from WYAIT (while you are in there), so while I was getting my crushed exhaust repaired, I might as well address the bad Y junction WIWIT.

Since blending two tubes to make a smooth "Y" junction is not very easy to do, I decided to buy a pre fabricated "Y" pipe. I found that Magnaflow made one that suited my purpose. I took some measurements and decided that the 2" in and 2.5" out was the perfect pipe. I then source the part online for $26.83 from Perfect.

Shawn's Muffler and Welding in Tahoe City is a local muffler shop. There might better and cheaper muffler shops, and I am sure there are worse and more expensive ones too. However he is close to my work and does pretty good work. He bent and welded in a new section of exhaust pipe as well as the new "Y" section. He charged me one hour for his time and the materials used.

Preliminary result show a return of my MPG and a little more pep. No additional exhaust volume, maybe a deeper tone. Throttle response is a quicker and ass dyno estimates a 5hp gain.
Vroom vroom!!


  1. This comment has been removed by a blog administrator.

  2. Thank you for posting such a useful, impressive and a wicked article./Wow.. looking good!

    Truck Mufflers

  3. This comment has been removed by the author.

  4. What did he charge you for the work?

  5. Thats a GREAT article & story specially for frontier owners.Ive been looking for some tips on how to fix that stock bent 2 in 1 muffler & of course hp. thx for info.

  6. Thanks for details describe. Easy to understood with pic. Good information.