So just a heads up but this might get a but wordy. :/

Today I finally got some time to do a few things to my truck at my buddy's shop. One including changing the intake spark plugs...20k miles late. After ripping one of the boots on the coil which was practically melted to the plug, and having to have a new $30 coil delivered (no one local carried just the replaceable boots), I decided to take it to one of my customers next week who has a garage and let him change the other 6. Great, I get to spend MORE $.

Anywayyyyy, I also wanted to take off the exhaust resonator in front of the muffler (how many freaking mufflers do these things need?!?) but quickly found out that it's a 2 3/4" system, not 2 1/2" like I thought. And NO ONE here carries 2 3/4" exhaust tubing. So my day was just getting better and better...

So after all that, I also decided to try a theory and take off my K&N intake and go back to the stock airbox and plenum with a K&N drop in filter as an experiment. I've seen guys talk on here that these 4.7s seem to like a little restriction, so I thought I'd try it out and see. Now keep in mind that I have a SC tuner and 3.92 gears with 33" tires, but...and this is where it gets crazy...after going back to the stock air system, I swear on all that's holy that the truck seems QUICKER than it did with the K&N intake setup. And not only that, it runs wayyyy smoother too. Acceleration and deceleration seems is smoother and predicable than it was so I think I may just stick with it for now. The only thing I don't know is what it's going to do to mileage. I only get 13 around town so hopefully it will improve, since every thing I've done to this pig has dropped the MPG. Which is really awesome when regular is $2.30 a gallon.

The only other thing I may try is seeing if taking the plenum back off and going with an intake tube from the air box to the throttle body may help. We'll see. And I'm ordering a 2 3/4" pipe online to dump that silly resonator

On another note, earlier this year I put a 2 1/2" level kit on the front and 1" blocks in the back and slapped some 33" BFG ATs on it, but haven't got any pics of it yet to post here. It looks way better than it did before though. Actually like a 4X4 now!

 

I've seen 11.5 mpg. But damn it's cold, gotta warm that thing up for my baby girl. It's normal to feel less low end grunt when you open up the intake or exhaust, your peak numbers are higher though, no doubt. You just may never feel the gains under normal driving or even spirited driving. But luckily the 4.7 peaks torque at just under 4000 rpm, so we will usually feel the gains by then. You should be able to make freeway passes a little easier.

 

Thanks. And yea, the low end DEFINITELY picked up going back to the stock air system. Several times the last few days I've actually broken the tires loose under takeoff (and mine is AWD!). One downside I've noticed tho is that the readout is now saying 11.8 MPG. That's a full 2 MPG decrease from before the plug change and going back to stock air intake setup.

I wonder which has more to do with the decreased mileage, the plugs or intake, or a combo of both...

 

Winter blend gas also causes lower MPG's.

 

It was reading 13.8 the day before the changes to 11.8 within a couple days after :/

 

Holy hell, I have not seen you around in awhile! How ya been?

Those are some oddities. My truck typical sucks the fuel in the winter, only because I love the remote start a little too much.

So the 08+s have a 2 3/4" pipe or are you just special, lol? Speaking of which, I do have a nice, brand new in the box 2 1/2" MBRP tip I need to put up for sale

 

Have been exhaust shopping for the last 2 weeks. A lot of reviews I've seen talk a lot about 2 3/4 pipe on the Daks.

EDIT: Just measured mine. 2.5 at the exit. 2.5 before the muffler ( measurement is over 2.5, but not close to 2 3/4 ) Will have to see if I can find those reviews that specifically talk about 2 3/4. Mine is a 2010 3.7. Not sure if the 4.7 had bigger pipe.

 

Myself and a mechanic buddy of mine calipered the pipe by the resonator and it's 2.72". Beats me if all the '08+ Dakotas with the 4.7 are the same exhaust diameter or not.

Doing good lghtngblt, thanks for asking. Just livin' the dream, ya know? :/ Oddly enough, I sold a brand new MBRP exhaust system after my '05 got wrecked. Haha

I actually hadn't even thought of that but I've been warming mine up the last few days before I leave to go anywhere. That would certainly show a lower MPG reading!

Damn, winter came early in NJ. Brrrrrr

 

If its 2.72, thats outside or inside diameter? Traditionally, pipe is measured inside diameter. So 2.5 sounds right. Tubing is measured outside diameter.

 

2.72od