Stock Flex pipe elimination, bad?

[Xavierviana]

Is there any risk if I eliminate the passenger side stock flex pipe? Vibrations? Hesitation? Rattling?

Appreciate any advise..

Thanks


X V

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[Anthony 05 GT]

I did one the Lethal Performance resonator deletes back when you could get it with the flex pipe delete too. It's been fine for a few years.

 

[NightmareMoon]

You're more likely to crack something and develop a leak without some give in the exhaust.

 

[Xavierviana]

You're more likely to crack something and develop a leak without some give in the exhaust.

Ok, the reason I ask is because I can see burn marks on my flex pipe, I think its a sign of a leak on the flex pipe. I can also hear minor rattling if I hit it with a rubber hammer.

Im thinking of replacing it with a straight pipe.

but now my question is, why is there only one flex pipe at one side of the exhaust.. is there more vibration in the passanger side that Ford put a flex pipe only this side of the exhaust?


Thanks for the advise.


X V

 

[Kevin]

Stock flex pipe rattled like crazy for me. I ended up getting an exhaust wrap on Amazon to muffle the rattle. Sidenote, it was creating false knock and bothered me to no end. Seems to have mitigated most of that now.

 

[BmacIL]

Stock flex pipe rattled like crazy for me. I ended up getting an exhaust wrap on Amazon to muffle the rattle. Sidenote, it was creating false knock and bothered me to no end. Seems to have mitigated most of that now.

The exhaust wrap got rid of your false knock? How much were you seeing before it?

 

[Kevin]

Base tune 91 w/ pmas intake I was getting as high as 6 on WOT 3rd gear although typically it was around 2.5-3ish. On WOT knocks showed up as early as 3.8k rpm sometimes but usually by 5k it was there. Similar knocks regardless of 91 or race fuel. I also removed the catch can, intake heat shield, and engine cover just in case. So the car only has an intake and cbe in terms of mods as a point of reference.

I added the wrap and removed the parts over the weekend, and I've had a couple WOT runs with 0 knocks but mostly with 0.1 to 0.5ish starting around 5.3k or so, which I think I can live with (I'm still certain it's false knock). The wrap was only $12 or something and it came with steel zip ties. I figured it doesn't hurt to leave it on.

Not sure if it'll help you but when I banged on the exhaust, the only rattle I heard originated from the flex pipe. I don't hear much of it now.

 

[BmacIL]

Base tune 91 w/ pmas intake I was getting as high as 6 on WOT 3rd gear although typically it was around 2.5-3ish. On WOT knocks showed up as early as 3.8k rpm sometimes but usually by 5k it was there. Similar knocks regardless of 91 or race fuel. I also removed the catch can, intake heat shield, and engine cover just in case. So the car only has an intake and cbe in terms of mods as a point of reference.

I added the wrap and removed the parts over the weekend, and I've had a couple WOT runs with 0 knocks but mostly with 0.1 to 0.5ish starting around 5.3k or so, which I think I can live with (I'm still certain it's false knock). The wrap was only $12 or something and it came with steel zip ties. I figured it doesn't hurt to leave it on.

Not sure if it'll help you but when I banged on the exhaust, the only rattle I heard originated from the flex pipe. I don't hear much of it now.

I have some buzzing/rattling in the exhaust but it doesn't seem to come from the flex when I hit it with a mallett. I am also seeing as high as 5-6 deg if I hit the throttle hard. If I roll into it a little, no knock all the way up to 7500+. As a consequence, between fast shifts I usually see some KR and it stays at that level until I let off, so it pulls a good amount of timing. I may order some of that wrap...found titanium wrap with steel zip ties for relatively cheap.

My video of it here:
https://www.mustang6g.com/forums/threads/chasing-false-knock.36141/page-5#post-2316300

 

[Xavierviana]

Why not just remove the flex pipe and replace it with a straight pipe ??

 

[Kevin]

For me, I don't have the tools or the know how to weld.

 

[Xavierviana]

For me, I don't have the tools or the know how to weld.

Muffler shop?

 

[BmacIL]

Why not just remove the flex pipe and replace it with a straight pipe ??

Because it's a good idea for exhaust durability to have a flexible section somewhere near the engine.

 

[moffetts]

I know this is an old thread but I wanted to put up my experiences with this if anyone else can get some use out of them. I have been seeing 3-4 degrees of knockr on the Whipple tune at very low RPM and low load, like taking off from a stop sign in first. This behavior was not affected at all by fuel; 91 and 91/boostane performed the same. WOT behavior is largely fine, but routinely pulling 4 degrees when driving normally at low load was driving me crazy. I started checking on my exhaust and confirmed everything was tight but there was a buzzing sound when hitting the area around the flex pipe. I don't have the ability to put it on a lift or jack stands (bay area life) so I took it to an exhaust shop. From his description, it sounds like there are some metal tabs on the exhaust clamps just downstream from the headers. One of these was touching and was causing the vibration. They took a screwdriver and created a slightly larger gap and the buzzing went away. I have only driven a short distance so far but the knockr is gone. I wish I could get some pictures of what he was referring to, but if you are getting the vibration and still have clamps in that location (ie, no LTH) then I would definitely give it some attention.

 

[Xavierviana]

I know this is an old thread but I wanted to put up my experiences with this if anyone else can get some use out of them. I have been seeing 3-4 degrees of knockr on the Whipple tune at very low RPM and low load, like taking off from a stop sign in first. This behavior was not affected at all by fuel; 91 and 91/boostane performed the same. WOT behavior is largely fine, but routinely pulling 4 degrees when driving normally at low load was driving me crazy. I started checking on my exhaust and confirmed everything was tight but there was a buzzing sound when hitting the area around the flex pipe. I don't have the ability to put it on a lift or jack stands (bay area life) so I took it to an exhaust shop. From his description, it sounds like there are some metal tabs on the exhaust clamps just downstream from the headers. One of these was touching and was causing the vibration. They took a screwdriver and created a slightly larger gap and the buzzing went away. I have only driven a short distance so far but the knockr is gone. I wish I could get some pictures of what he was referring to, but if you are getting the vibration and still have clamps in that location (ie, no LTH) then I would definitely give it some attention.

If you have a possibilities to get picture of the clamps and tabs, that would be nice.

Thanks for the advice.

XV

 

[moffetts]

I am guessing that this is what he was referring to.

https://imgur.com/a/8aIy54v

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