A couple of weeks ago I finally got my exhaust redone. Cat-back custom with a Magnaflow muffler. I did mine the same way that mtbpath and bberman did. I am sure there are others out there that have done the same.
See mtbpath's topic below on his exhaust.
http://thenissanpath.com/viewtopic.php? ... =magnaflow

With the new exhaust in place, I had to take it to the dragstrip to see what kinda gains I would get, if any... I put the K&N cold air intake kit on a couple of years ago and had practically no gain in my 1/4 mile times. I had hoped then that eliminating the restrictive "Y" before the muffler would be the secret to success.
See my 1/4 mile results from back then, on the 3rd page of my A/M air intake topic.
http://thenissanpath.com/viewtopic.php?t=481&highlight=

I must say I am pretty happy with the results!! My best time Friday night was a 15.08 @89.36. My previous best time, with only the K&N, was a 15.28 @89.52
I gained .20 in my ET.

A couple of things to note here...

1. I now have 50,000 more miles on my Pathy than I did 2 years ago, the last time I took it to the strip. I am now a firm believer in synthetic oil!!
2. It was 15 degrees warmer this time than the last time.

FYI, I dropped the spare tire, took out the jack tools and any of my crap I carry around regularly. I did the same on all my previous trips.

Getting into the 14's wont be too difficult. I bet I would have been under 15 if it had been 45 degrees outside again. I could also let just about any friend race it for me and it would get into the 14's... most of my friends are much smaller than me.

If you got a programmer to actually take into account the add-ons, that would help even more. Not many of those type of things out for the Pathy though. One thing you could do is disconnect the battery for a while, so the truck relearns things. Drive aggressive for the first tank and that should work. Of course that is one of those internet rumors, so I don't know if it will actually work.