OK, I'm new to the diesel world so if this sounds like a dumb question...sorry.

What should I invest in first, a tuner or an exhaust...I can probably get myhands on about $350-400 quickly and was curious which one to spend it on.

 

Exhaust, then gauges, then a tuner.

 

for my v10, the tuner was so much more dramatic. There was a very perceptible difference. I then changed the exhaust and intake with a K&N FIPK but those did not make the difference the tuner did. Maybe diesel is different. I dont have experience with those.

Anything you do to improve the performance is worth it. Good luck.

 

The truck already has a K&N performance injection intake and filter (they were there when I bought it). I also found that i need to put new bushings in the sway bar, so that will definately be first on the list. But I do have to pull a 33 foot TT with it so towing efficiency is HIGH on my list. I know that keeping it under 2k RPM will help...but...

 

I 2nd williamX

 

If it's a diesel, I didn't see if it is a diesel or a gasser, but, if it's a diesel, exhaust.

 

IMHO... you don't say which diesel.... but for any turboed diesel, I would pull the K&N off in a heartbeat and sell it to get the money for my tuner... (some have said it allows too much dust into a turbocharged vehicle)

A good SCT tuner will help tremendously, but can generate heat quickly (like all tuners!)

While I wanted to do the right thing...
money for gauges, etc... wasn't hi on the priority list...

If u want to do what I've done...
As a temporary measure and having had a full turbo back exhaust on my 03 6.oh I opted for a $60 Walker BTM muffler with lifetime warranty from my local NAPA Auto Parts in place of the stock muffler and called it good (others with gauges had tested the difference and saw 250 degree drops in temp with this one change)
http://www.blackclouddiesel.com/Ford/walkermuffler.htm

then got a hot tuned sct from Innovative and all have performed well for 107k+ miles...
and then I called it MUCH better !!

so just my experience...
I have tunes from at least 4 other tuners and while they may work well for others, didn't for me.... either they didn't hear/listen to what I wanted or not up to the task (IMHO again )

good luck, but be forewarned, once you put a tuner on, going back to stock is 'turrible'

and watch your tunes if you are towing heavy.... (chk with the tuner for the weights you will be pulling)