Any thoughts?

 

I installed the Banks Monster Exhaust with a True Flow XDI CAI

I did not get any added benefit for MPG but the Jeep is louder

 

There are some theories about "tuning" that might hold true in some instances. However, the stock system likely is not much of a restriction. This is especially true since the vast majority of driving is not at WOT or at high RPM. I suggest, unlike many opinions, that DCX designed the exhaust just fine.

Be careful about the answer you get. I took a trip this weekend. I used my scan gauge, my dash gauge, and manually calculated my mileage. The scan gauge could get within about .2 MPG no matter what the conditions. That is likely as good as my manual calculations. The dash gauge was off by 4.5 mpg at one stop and never got it right for the rest of the trip!

 

I wouldn't expect any miracles.

 

geez......

 

To me, cat backs are just like stripes or fancy wheels except that they are for sound where stripes and wheels are for looks.

To get any real benefit from exhaust changes you have to go from the engine back with headers and such. But then you open up all sorts of issues in tuning and engine mods like intakes. It has to be a complete package to work

You also have the problem of whether or not you can do these changes and still be streel legal.

Ask yourself "Are you building a racing Jeep?"

Personally, I'd put my money in trail mods.

 

I had 1.3MPG before my cat-back Now I get 1.5MPG

 

Absolutely incorrect. While the greatest amount of change would certainly come from a complete system overhaul, improvements are made thoughout the performance spectrum. I guess I would have to ask what a "real benefit" is? Would a small increase in horsepower with no added fuel mileage be a benefit to you? how about a fuel mileage increase with no added HP? In most of the cat-back exhaust systems the back-pressure of the exhaust is relieved enough to make small gains in HP. Mileage beneifits vary greatly, however, over the lifetime a vehicle a small change can add up to a large difference. But as always, a cost/benefit analysis needs to be done: did spending $500-$700 on the exhaust lead to 150-200 gallon savings over its lifetime?? OK, alot of big thoughts there, but in the end, your statement on the exhaust system is flawed.

 

I do have to agree with you on many of your points. But as for me, if I am going to invest large amounts of money, and I consider $500-$700 a substantial amount, I perfer to see more than incremental gains in performance and economy.

I stand by my statement that real benefits, meaning substantial gains in HP, economy or both, come from working the engine package as a whole.

 

The real benifit in changing the exhaust is getting it tucked up out of the way and hopefully protected.
I crushed the crap out of my stock muffler on my 2dr X the 1st day I had on the 35's on my 3" lift.
With no where to go with relocation etc. I just put in a small gibson flow thru and a 1/4 steel custom skid over that.

Before that I had added a CAI and noticed a small gain in power.
With the flow thru on that gain went away.
It sounded better tho...pffft

I suspect the Jeep is tuned for the back pressure.
But really I have no idea.

All I do know is that skid plate under the new muffler sees a lt of rocks.
I have since crushed the tail pipe.
So I am gona figure out a way to run a hole through the bumper and put it thru that to protect it too. grrrr