I have the magnaflow high flow cat. I like it. I do have larger tires and never changed my gear speedo so my MPG is off, so I'm not sure if its better than stock MPG. It feels quicker, but I also did in conjunction with a bunch of other mods so its hard to tell for sure.

I am currently upgrading (???) to the Banks Torque Tube Exhaust Manifold and I am using the gasket that came with the kit. I was planning on using the swivel washers for the intake and exhaust installation that I removed from the original set up, however there is difference in the intake to exhaust manifold thickness; will the swivel work?, the difference in mine is about 1/32" in most areas and up to 1/16" in a few others, I noticed that the intake flange had areas where it looks as if the washer seated in well past the flange surface. Also, are there any tips for the Dual cat Down Pipe installation, I got the pipe from OMIX ADA and it is a single pipe (with dual CAT's) to the other CAT, I have it up and in, just have to pick up some Exhaust crush seal gaskets for the pipe to header final install. I appreciate any comments.

Sorry if this has been repplied to a million times, but with 312 Pages I couldn't find it...

I have an exhaust leak between the exhaust manifold and the cylinder head. It is caused by the front and rear mounting studs broken off. I believe I have to drill them out and make new threads? Anyone know the length/depth, and pitch? Should I replace them with studs again for easy assembly, or just go for bolts as all the other mounts?

I went with the Dorman 03408 kit which includes new studs and all new bolts. I did, however, reuse the manifold washers to make sure I got a good "bite" on both the manifolds with the bolts. I also used anti-seize on all the bolts and rear stud. On the front stud, I used teflon tape since it shares the hole with the head stud that goes through the water jacket.

https://www.rockauto.com/en/moreinfo...=1180112&jsn=2

Do yourself a favor though and remove the head to drill it. I thought I could just use a 90* drill on the one at the back of the head and be fine.... until the drill bit started to walk on me:


Click for full res


Click for full res

Thanks, great info. Ordered that Dorman-kit now.

Any time. Don't forget the head gasket, while you're ordering parts. And remember, the head bolts can be re-used ONCE. So if you think that head may have been off of there already, might want to look into replacing them as well. Also, there's a torque pattern for the head as well as the manifolds. To add to it, there's torque "increment" for the head as well.

Here's the pattern for the head:



The increment sequence (per the FSM) is:

step 1...tighten all bolts to 22ft/lbs
step 2...tighten all bolts to 45 ft/lbs
step 3...recheck all bolts at 45ft/lbs
step 4...tighten all bolts except #11 to 110ft/lbs, then tighten #11 to 100ft/lbs

The pattern for the manifolds is:

I just ordered a new exhaust system from the exhaust manifold to the tailpipe, and after inspection it appears I accidently bought a catalytic converter that has a 2.00" ID and 2.00" OD. I am worried about flow, if this would be too restrictive? Would I be okay installing it with the rest of the 2.25" exhaust and using adapters to make it fit? Or would it cause problems?

Can you return it? A lot of people prefer 2.5 to the factory 2.25 exhaust. I would be nervous about making my exhaust more restrictive than it came from the factory.

Thanks again, Basslicks.
Do I understand You correctly in that the front exhaust stud bolt hole should be drilled all the way into the hole for the head bolt # 11? And that the head bolt enters a cooling channel, and therefore I need some sealant on both that head bolt and the stud?

Definitely get a bigger high flow cat

Larger exhaust and high flow cats/mufflers are only helpful if you have done considerable engine mods for them to make a difference.


If you have installed large tires and not gears you will see a considerable gain in performance going to a lower gear ratio, that you will feel seat of the pants. I went to a 33" tire stock gear for a while then changed from the 3.55 to a 4.56 gear and not only a real difference but gained almost 5 mpg highway and trans didn't up/down shift all the time either after that.

I wouldn't have thought going to a lower gear ratio would increase mileage. But engines are fickle like that, rpm ranges are more and less efficient, less load may make it run more efficient etc. I would still not undersize a catalytic converter though, I still say get a bigger one, even a high flow or bigger than stock, then if you do some mods later you don't have to change that again. It seems like mine is all 2.5" cat back, dynomax super turbo muffler, runs pretty good.

So I've got a question. I just bought a Jeep Cherokee in line 6 and the kids I brought it from cut the Cadillac converter off. Here NM we don't have emissions test. The check engine light came on so I took it to Auto zone. They diagnosed said it was cadillac converter? So I assumed it was the sensors on it. It still ran so I drove it for few weeks drove it off and then I changed the oil to synthetic oil. Then bomb all sudden it would only start and stay running if I kept the pedal down and rpm high. Onse I left off it just dies? So what yall think?

Its not really the forum for that question, but I would start be cleaning connections everywhere, but mostly at the Throttle Position Sensor, had that happen to me before, cleaned the connection and it was good.

No. 2" is way too small for a 6 cylinder engine.

Drilled that way from the factory, yes.

To clarify, the HEAD BOLT needs teflon tape on it because it goes into a cooling jacket in the engine block. That particular bolt also runs along side the thermostat housing at the front of the head, but I don't believe it goes "through" it (I'd have to look, I honestly can't remember). So I put teflon tape on the front exhaust manifold stud as a precaution, just in case any water made its way past the head stud. It's not required, just peace of mind for me.

The idle problem is quite possibly the Idle Air Control motor. Hooks to the throttle body and allows just enough air to pass through so that the motor stays running.

Asking here https://www.cherokeeforum.com/f2/ask...772/index3840/ will yield better results.

As far as the catalytic converter goes, regardless of what your state's inspection process is, Federal law states all vehicles that came with a cat must be equipped with one.

What year is your Jeep? Later model Jeeps had downstream O2 sensors and the 99-01 California emissions models had a total of 5. 2 o2 sensors, 2 pre-cats, 2 o2 sensors, the catalytic, and the downstream o2.