While wheeling in CO, I made some poor line choices while taking my overloaded rig down engineer pass. I ended up with a nice dent in my exhaust pipe. I was going to try to weld a tab to it and pull it out, but im not excited to weld on the pipe (poor skill, potential weaking of metal, holes, future corrosion etc). Ive already ordered skids.
I got to looking at the pipe closer and saw that immediately downstream, the pipe goes from 61mm to 48mm diameter, then the pipe combines to the right side and all 6 cylinders are carried by the 61mm diameter pipe. I think that dent restricts 25% flow (very rough area calculation) but that 48mm pipe restricts 40%.
I think im going to leave it as the dented area is volumetrically larger than the smaller pipe before y junction. I have not seen any drivability issues. Let me know your thoughts. Im sure im way overthinking this, but these rigs are not cheap and i don't want to damage the engine.

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The only thing I'd think about is that anytime you have airflow through a pipe system and there's a non-smooth or ridged surface you risk some kind of flow issue like a Bernoulli effect happening. It's possible that with the particulate nature of exhaust you'll get a swirling effect caused by the dent. That could cause backup. Just a guess, and probably not likely, but seems possible.

How much would it cost to just replace the pipe at the bolted area? Looks like that's a fairly easy replacement.

Good thought on the swirling effect. Honestly i didn't check on repair from exhaust guy. Im reluctant with a cut and replace job because ive seen aftermarket materials be inferior in long run. Ive replaced exhaust pipe on cars just to see it rust at alarming rate compared to oem. Maybe in long run, ill get some super sweet upgrade system!

If it was me, and I was having it repaired, I'd look into rerouting that crossover.
Similar is done with the "tummy tuck", that I'm also interested in doing.
5th Gen Tummy Tuck = ground clearance - Toyota 4Runner Forum - Largest 4Runner Forum


5th Gen Tummy Tuck = ground clearance

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I agree I’d have it fixed

Not sure about pulling that dent out, but there is a lone aftermarket Y-pipe out there from URD that addresses the flow issue. (Fixed Link for 2010+)

Personally, I'd drive it and watch for any changes. If MPG stays the same, that's probably a good indicator that all is well. Plus, the pipe likely widened at least a little in response to the upward blow. Inspect it periodically. If you do observe any problems, you can get it fixed at that time.

I did a very similar thing to a car many years ago, and never did fix it, and didn't have any noticeable problems, either.

And then add a full suite of skids.

On many trails, hitting/sliding there is simply unavoidable as the breakover angle is what it is.

Rerouting is also a great idea.

Agreed. Also, note that the tubes in and out of the catalytic converters are smaller than this tube. This tube also conveys only half the exhaust, the left cylinder bank.

You might consider a modest lift/leveling kit. Spacers are economical and can raise the front up to 3" which will help in future situations. As others have suggest, a full skid plate, such as those from CBI or RCI could be used.

What dent? Seen worse. Replace if you get an exhaust leak.


Drive on.

I thought those Y-pipes aren't compliant. Especially for those who live in states with strict smog/registration compliance laws.

They're certainly not compliant with wallets.

Holy hell.


Dent doesn't look horrible. Sound change? MPG change? If yes, then get it fixed.

Oceanside , Cali ? Have visual inspection ? Nv does not so why I'm running both my 4r 11'& 14' delete to cats & will not throw code ! Otherwise have muffler shop fabricate a y-pipe or cut that piece out ! Besides heat shields this a bad spot anyhow because it hangs below the transfer case bracket , my 2 cents !

hmmmmm
so youre telling me you need a new URD offroad y pipe.

URD Off Road Y Pipe for 2010+ 4Runner V6 - Underdog Racing Development

These remove the downstream cat, hence not legal for communist states unless you have the shop weld another cat in. It's also why they're considered an "off-road" y-pipe.