Seafoam exposed one leak that I could see ... inside the flange between the header and downpipe ... Will give it another gasket and new bolts if needed ... then retest ...

A leak before the upstream o2 sensor can sometimes produces a false lean ... could be the PCM is providing to rich a/f ratio at certain rpms ..

I noticed while in park, high rpms (rev engine), smoke comes out from the flange (indicates some sort of back pressure) ... lower rpms, there is no smoke, seems to be sucking air (oxygen) into the exhaust ...

 

How much difference in sound is there between a turn down before the axle and piped out the rear? I was told you get better sound by piping it out the back.

 

I tend to go with turn downs because I like quiet exhaust..the turn down echos/reflects the exhaust off the ground back up inturn making the exhaust louder than it actually is!
If you can understand that lol..kind of a oxymoron! I had my tail pipe out the rear & I personally didn't like it! I think it sounds meaner with it being dumped! It sounds the same just louder!

The longer the exhaust the quieter it will be! Its that simple, so the tailpipe will quiet it down to an extent! I say turn down and be down!

 

Haha I seafoamed mine and found a leak there as well. I left it alone..doesn't cause any problem I can see..runs the same. But you can hear the clicking sound coming from it...
The smoke your seeing is probably a little oil burning off...blow by. Mine does the same also but only when its cold..once its heated up I don't get any smoke..if you started noticing the smoke after the seafoam it could be from that as well!!
No issues in my rig and I run it to 5k daily! 300K+ miles and I treat it like a race car very often...never skips a beat!

 

It only smokes while adding Seafoam ... otherwise it runs ok ...

Gas mileage seems to have gotten worse . ... since around ~50,000 miles ago, various changes were made by muffler shops to the exhaust, which use to be completely OEM stock, using the old style cat.

 

You want mpg back!
Answer this, has it been lifted? What kind of tires? Hows it being driven?
I would check the header for cracks..if its cracked by a new one..perferably a APN! Get that downpipe remade...full 2.5" and add flex pipe so the header will stop cracking!
Get a new cat if needed!

 

Putting a tailpipe on it will make it much smoother sounding.

 

x2...i've ran both, and with it all the way out the back it sounded much cleaner.

 

It has an OME lift with 235's A/T ...

Currently it is not being used daily and is equipped to pull a trailer or to be flat towed. I like to go off-road, sometimes over 100 miles, and need to carry extra gas. If going on a longer trip e.g. 500 - to over 1000 miles a difference of ~5 mpg becomes significant ... requires more stops to fill up. Some areas do not have gas stations and you have to bring your own petrol.

 

Ya the lift and tires are hurting it some...but you should be able to improve it!
I mean my 5 speed 4x4 is raised 3" with 31" muds...I'm getting 19 in town
I love my 5speed!

 

I try to keep it so it can run in most climates and road conditions without problems ... the exhaust needs to be looked at again . ... Haven't checked fill-ups really close but think it is getting around ~14 mpg

If your competing with logging trucks muffler noise usually isn't a problem ... my muffler finally got broke in ... doesn't sound really loud ... it's those quiet areas with vehicles that you can't here sneaking up that I worry about ... some can't be heard until there a couple of feet away ..

 

Spintech 9000 installed.
This thing sounds BADMOTHER****INASS. Standing next to it puts a nice vibration in your chest... I'll get vid later. Need to add the turndown still. 2.5in with a poor man's adapter to 2.25.

 

Told ya. Usmclovesxj ya shoulda listened. Those mufflers sound amazing! I can't wait for the 6000. The 3000s on my stang are the best sounding mufflers I ever heard. How loud is the 9000? Does it drone inside?

 

I know this isn't JEEP related...but i was trying to hear the spintech on a 4.0 and came across this...IMO i think the 10 sound way better...lot meaner and louder...plus the 9000 sounded really poppy.

 

Can't even hear it over my tires when I'm driving. So I can't tell you if it drones or not lol