my91cherokeexj

Hey CF people. i had a question. i have a 1991 XJ with a cherry bomb glassback with no cat. i want to upgrade the exhaust to something more mature. don't get me wrong i love the cherry bomb and sound, but i want it more smooth looking overall and sounding. so i was wondering what cat should i get? nothing too expensive either. and i also was wondering which catback exhaust system sounds really good on the 4.0L? again nothing too expensive. thanks for any help.

brutalxj

You don't need a cat save that money and buy a flow master they sound sweet a cat back is a good idea to save money you can buy a dynomax cat back but without the muffler and then use the flow master muff. The flow has a much deeper and more consistent sound then the dynomax muff.

zman32006

Exactly! I have a cat-back exhaust system with no cat on my '90. before I had a stock exhaust system with no cat, it made my jeep quieter and actually gave me like 1.5-2 more mpg's Id say go for it. I got mine off ebay brand new for like $125ish

Edit: sorry I forgot to mention that its a Dynomax Cat Back Exhaust system

boneguru

I wish I could run with no cat but they check us every year in an inspection for registration....

zman32006

luckily in GA there are no exhaust laws except for noise ordinances. Other than that we're good to go. Greenies dont like it but theyre full of it anyways.

my91cherokeexj

okay thanks man. sounds like a plan. oh and does anyone know where to get the rubber exhaust hangers? mine are rotted out

zman32006

you can get them at auto zone or advance auto or orielly's

96_xj

you NEED to run a cat...

here is one for us Cherokee Forum members:
https://www.cherokeeforum.com/f10/ou...nverter-45340/

i hear good things about it

zman32006

why do I NEED to run a cat? jw cuz I dont have any laws that say I do.

96_xj

it is a federal law.

(also talk of not running a cat is against forum rules).

zman32006

Oh sorry I wasn't aware it was against forum rules, I won't do it again. but it is not a federal law, it vries state by state and in georgia there is no law that says you have to run a cat... Yet

96_xj

according to the DMV these are the tests they run at the inspection station:

All 1996 and newer vehicles will receive a two-part inspection.

An OBD test to check your vehicle’s emission control performance history.
A fuel cap inspection to check for adequate seal.
If an OBD test is unable to be performed on a vehicle, it may be necessary to perform a Two-Speed Idle test (TSI).

All 1995 and older model year vehicles will receive a four-part inspection:
A visual inspection of the catalytic converter to check for tampering or removal.
ASM2 or Accelerated Simulation Mode Test - A dual-mode test including a 25/25 test = 25 percent load at 25 MPH and a 50/15 test = 50 percent load at 15 MPH.
A tailpipe exhaust emission test.
A fuel cap inspection to check for adequate seal.
An inspector can reject a vehicle for testing if it is considered unsafe to test. If the test has already begun when the safety problem is detected, the inspector may charge the full price of the test.

i found these laws for georgia on exhaust lol

§ 40-8-71. Exhaust system; prevention of noise, smoke, and fumes
(a) Every motor vehicle shall at all times be equipped with an exhaust system, in good working order and in constant operation, meeting the following specifications:
(1) The exhaust system shall include the piping leading from the flange of the exhaust manifold to and including the muffler or mufflers and tail pipes;
(2) The use of flexible pipe shall be prohibited except on diesel tractors or according to manufacturers' original specifications;
(3) The exhaust emission point shall extend beyond the rear or outside of the passenger compartment. The trunk shall be considered as part of the passenger compartment;
(c) It shall be unlawful for any person to sell or offer for sale any muffler which causes excessive or unusual noise or annoying smoke or any muffler cutout, bypass, or similar device for use on a motor vehicle or for any person to use, to sell, or to offer for sale any motor vehicle equipped with any such muffler, muffler cutout, bypass, or similar device. Any person violating this subsection shall be guilty of a misdemeanor.

**nothing is stated about a cat tho.....

it just stated all you need is a muffler for noise and piping lol.

altho this law must suck(not like its followed....)
§ 40-8-6. Alteration of suspension system; operation of vehicle with broken springs
(a) It shall be unlawful to alter the suspension system of any private passenger motor vehicle which may be operated on any public street or highway more than two inches above or below the factory recommendation for any such vehicle.
(d) Any person violating this Code section shall be guilty of a misdemeanor.

96_xj

this is the US Law:

Rules for Replacing Converters
In 1986, the U.S. Environmental Protection Agency issued new guidelines for the construction, efficiency and installation of aftermarket catalytic converters. All CleanAir converters listed in this catalog have been designed, tested and manufactured to meet this policy.

In addition, CleanAir converter listed in this catalog is appropriate for use under the current requirements of the California Air Resources Board (C.A.R.B.).
E.P.A. guidelines state that replacement converters may be installed only in the following situations:

1. The vehicle is missing a converter
2. A state or local inspection program has determined that the existing converter needs replacement
3. Vehicles manufactured prior to 1996 must have more than 50,000 miles, and a legitimate need for replacement must be established and documented
4. In cases of OBD Il-equipped vehicles (1996 and later), the O.E. manufacturer's 8-year/80,000-mile warranty must have expired and a legitimate need for replacement must be established and documented.
Please note that Federal law prohibits removal or replacement of a properly functioning O.E. converter.

When replacement of the converter is appropriate (as outlined above), the E.P.A. further requires that:

1. It be installed in the same location as the original
2. It be the same type as the original (i.e., two-way, three-way, three-way plus air/three-way plus oxidation)
3. It be the proper model for the vehicle application as determined and specified by the manufacturer
4. It be properly connected to any existing air injection components on the vehicle
5. It be installed with any other required converter for a particular application
6. It be accompanied by a warranty information card to be completed by the installer.

zman32006

well thats something I didnt know. learn something new every day but until the epa comes knocking on my door ahahahaha

Veeb0rg

Dynomax has a 75$ rebate on their catback systems currently.