So I have my factory exhaust pipe and realize that there is a dent just after the headers, after further research this is supposedly a factory thing??? Not sure if it is or not but I'm curious if it is because if so I'm not gonna worry about it as it's intentional
but if it isn't the factory dent then I'll worry about replacing it.

 

It's factory. And stupid.
The purpose of the restriction dent is to decrease warm up times in Arctic conditions.
Making the dent was far cheaper than the vacuum operated exhaust heated intake air system used on 87-90 RENIX system Jeeps.

Dynomax and others sell dent free down pipes.
The engine breathes a little easier and runs a little cooler.

 

I remember the first time I had the exhaust off of my 99. thought something had happened. Nope, factory dent. Seems so stupid. Still on the factory dented downpipe on my 99. HAs 250k miles on it. Miraculously, still on the original catalytic converter.

 

Good to know, I doubt I'll deal with it now but later I'll probably be getting bigger headers and bigger tubes and get one without that dent, I rarely drive in arctic conditions anyway lol(like never XD) but when it's cold I just idle extra.

 

IIRC, there was also some speculation the dent was for driveshaft clearance at full flex, but I'm not sure if that's actually been proven correct.

 

If the FDS is high up enough to be next to the dent...your Cherokee is bent.

 

It's also on 2WD models, so it's nothing to do with the driveshaft. It was added to slightly alter the volumetric flow rate of the exhaust to help increase cat efficiency and put out better emissions numbers.

 

While I can't confirm Jeep's original intentions, I CAN confirm that with a high-pinion Dana 30 front axle, the drive shaft will come into contact with the front pipe/down pipe if there is NO dent.
I find the dent retarded as well, so I purchased a front pipe from ebay, and installed that. On the road it's awesome, noticeable improvement in climbing hills (I live in the mountains of Colorado, lots of hills on these highways).
And while I was replacing the yoke seal in that Dana High Pinion, I noticed my shiny new front pipe had been struck by the driveshaft, exactly where that dent was on the factory front pipe.
I'm leaving it alone, it's a lot less restrictive than the factory BS solution. I'm pretty sure it only happens while offroading, and probably while flexed to the max, like three-wheeling (I'm guessing it'd have to be while the driver's wheel is totally stuffed and the passenger wheel is totally extended, but I have not confirmed this).

All I know is the front pipe/down pipe will interfere with the driveshaft if there is no dent.

RELATED: I suspect this may be part of the reason my cheap headers cracked, but I cannot confirm that. I'm going to start another thread about cracking aftermarket headers. I hate doing this job, and the only thing I hate more than doing it is doing it again and again.