I've noticed that 04+ engines lack that massive "silencer box" that I have on my 03. I am referring to that big box with 3.7 V6 printed on it, right at the point where the tube from the air box meets the engine. What does this box do? What happens if I take it off? I have been considering adding an intake, and have read all about them on the forum, but nobody mentions that big box and how it fits into the intake equation...

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2003 KJ Sport
245/70/16 General Grabber AT2
MOPAR skids
Flowmaster Muffler
K&N Drop-In

It is an air silencer. I have the intake tube assy (w/out the silencer) off an 05 on my 03 and noticed no performance gain or loss. I will say the FIPK sure doesn't add anything performance wise either. My 03 has always been much more responsive than my 04.

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99 TJ
71 C101
04 KJ
03 SFA KJ Sport
LOST JEEPS So-Cal

so basically, if I want more engine noise, pull it off, and find some tube to attach in its place?

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2003 KJ Sport
245/70/16 General Grabber AT2
MOPAR skids
Flowmaster Muffler
K&N Drop-In

The noise isnt coming from the engine itself, but rather sounds very similar to when you use the handheld hose attachment on a vacuum cleaner. From the cabin when you're driving a car with an intake system, you can hear a slight whirring of the air as its being sucked into the throttle body. At WOT the noise is minimal, but you can hear it during stop and go driving when the throttle body is opening and closing.

That box, called a Helmholtz resonator (or resonator box) is designed in such a way as to make the incoming air waves acoustically cancel its own noise out, similar to an OEM muffler designed to make the vehicle exhaust noise as quiet as possible. Removing the resonator allows greater velocity of intake air and the suction noise to be heard. One or two of the models of cold-air intakes designed for our KJs keeps this resonator in place and has a tube extending from it leading to a cone filter in that same area where the stock filter would be. Most other models of intakes eliminate the filter box and Helmholtz altogether and just use a cone filter and tube that feeds directly into the throttle body.

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"It's not what you drive, but how you drive it."

02 Sport in Stone White
-AEM CAI, Borla XS muffler
-Duralast Premium rotors and PFC pads in front (rotors are cool but the pads suck); Satisfied pads in back drums
-6k HID mains, Hella 500 high beams
-Yokohama Geolandar HTS 235/70 R16
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