JK exhaust change.

[TheoB]

Hi guys,
Firstly my apologises if I ask a few stupid questions, as I'm new to Jeeps, but have had many other 4WDs in the past.

My initial question is regarding my 09 JK 4 door CRD manual. Looking to unleash the beast a little and was keen to ask what other JK CDR owners have done in terms of exhaust?

On my previous 4wd, I installed a 3" system from the turbo back (no cat) with a straight thru muffler. It was great initially, but then found with the variable vane turbo, the ecu fed more boost to the system and the car would error and go into limp mode (mostly while just cruising the highway at 100km loaded with pax and gear). We had to then adjust the VNC on the turbo so it wouldn't overboost and once done - it was excellent!!

Is this something that happens on the JK's as well?
Has anyone modded their exhaust and to what extent? What gains were achieved?

Thanks in advance.

[WHHEMI]

Hi and welcome to the forum I don't know if anyone has put a full system on yet , a lot of people just take off the rear muffler and put a tailpipe on in it's place I haven't done this yet but it's on the list.

[TheoB]

Thanks and cheers for that. I'd be keen to see what people have done from the turbo back effectively.
What are the downsides and upsides...?

[JasperJ]

Originally Posted by greenjk

Hi and welcome to the forum I don't know if anyone has put a full system on yet , a lot of people just take off the rear muffler and put a tailpipe on in it's place I haven't done this yet but it's on the list.

Yeah I dropped mine off ages ago, the turbo breaks up the resonance that the muffler is designed to negate. That's why it doesn't sound much louder without the rear muffler than without it. It does change the pitch a little but not overly loud in the cabin. Most of the time I can't hear it over the induction noise from the snorkel.

It does seem to have better bottom end but it's pretty minor and fuel economy is a little better. All up cost was <$50 to get a tailpipe made up. end result is 10 kg of worthless weight removed.

[drewinmanx]

Originally Posted by JasperJ

Yeah I dropped mine off ages ago, the turbo breaks up the resonance that the muffler is designed to negate. That's why it doesn't sound much louder without the rear muffler than without it. It does change the pitch a little but not overly loud in the cabin. Most of the time I can't hear it over the induction noise from the snorkel.

It does seem to have better bottom end but it's pretty minor and fuel economy is a little better. All up cost was <$50 to get a tailpipe made up. end result is 10 kg of worthless weight removed.

Yeah same same end result. The main reason I did it was to be able to fit a larger underfloor storage compartment for 2nd battery and other odds n sods.

I have dropped off a few rock ledges and scraped the muffler (when I still had one) much more clearance without it now.

[Yom]

There's sweet FA room to fit a larger exhaust under the JK CRD and the existing one is mandrel bent and a pretty decently sized unit to begin with.

May as well drop the rear muffler and put a straight pipe out the back.

Also the VM 2.8's turbo is variable vein but electronically controlled. Doesn't use vacuum so doesn't really suffer boost control issues like the ZD30. PS: don't play with the little arm on the turbo - you could damage things.

[TheoB]

haha Yom, you know exactly what I'm referring to. We had all sorts of issues with the ZD30 at one stage.
Good to know about the JK. Thanks.