BUYER BEWARE! One year review of my Doug Thorley Headers.

Hey all,

This is my first post here and I gotta say I'm enjoying the forums! Apologize for the long post. I Want to share my experience with my headers that I have had installed on my truck for a little over a year now.

So far the MPG gains and the performance gains are amazing! I frequently see 18 mpg city, and 21 highway and find myself going a little farther between fill-ups which is nice. They've woken the engine up and have made it sound like a true V8. All this is good but they're beginning to experience the killer of all cars. RUST!!!

I've attached the Imgur links to the pictures of the rost at the bottom of this post. They've started to rust just over a year of having them installed on my rig. Given the rust isn't too bad but having them rust is still quite a shocker, especially since they're advertised as being stainless steel. They're beginning to rust on the pipes and the flanges. Given I do live in New Jersey and the weather can be unforgiving But as you can see in the provided picture's they're rusting on the top of the headers and not the sides, nor are the bottoms rusted either.

I've been in contact with Dough Thorley and of course in efforts to cover their hides and quite quickly at that, they've stated that Rust caused by weather is not covered under their warranty. They didn't even ask what state I live in. they just responded with "Rust caused by weather is not covered under warranty. Sorry for the inconvenience".

During the production process for my headers, I received an email saying that they were going to be delayed. Curious as to why I called to see what was the reason and the rep that I spoke to said that they were having an issue with the ceramic coating company. He didn't want to go into too much detail as to what the issue was, but he said that they were having an issue of getting them back from the company for some reason. He reassured me that my headers would be fine so I went on with my day. A year later this doesn't seem to be the case. I included this in my email to them and they seem to have brushed right over it.

That being said they have been known to rust, unfortunately. Back in 2019, a post was made by Marfy (I don't know how to tag people :sad expressing his issues about these headers as well. at the time the parts that were rusting were the flanges and the air injection tubes. There was an update saying that he spoke to Mike from Doug Thorley headers and the issue has been addressed but it doesn't seem that it has. They still have rusting issues and it seems they have no intention of fixing it.

My main concern now is that these headers won't last as long as they should, and now I have to worry about the pipe's cracking again. It's really disappointing when these headers are advertised by many as a cheaper and more reliable alternative than an OE or an exact OEM replacement exhaust manifold. Take a lesson from me and AVOID THESE HEADERS!!!!! They seem to have a rusting issue that hasn't been fixed or they have an issue with quality control and are not robust as advertised to be. Thanks for reading!

Link to Marfy's post:
**UPDATE** - DT has made right - Buyer Beware - Doug Thorley Headers

Links to pictures:
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Imgur: The magic of the Internet
Imgur: The magic of the Internet
https://imgur.com/bd2736t

EDIT: Thank you all so much for the feedback! this is great information that I can use to find out why this is happening and to try to get them to work with me. But most importantly, This is hopefully a step forward to avoid this scenario from happening to anyone else if Doug Thorley truly cares about their customers and want to work on their quality control. I'll be emailing them again sometime today or tomorrow and will post feedback here. Almost tempted to send them this post directly but might not. One thing for sure is that I'm definitely going to try doing that magnet test sometime to clarify what kind of SS they are made of. I'm doing an oil change tomorrow so I'll do the test then. I'll report the results from that and will definitely update this post as I continue to talk to the kind souls at Doug Thorley headers.

EDIT 6/10/21: Hello again. This past week has been hectic so I haven't had the chance to reach out to them again. this past Monday while changing out the spark plugs, I found out that the secondary air injector on bank 1 is showing signs of rusting and pitting. It looks like the rust began at the flanges and is working it's way up the secondary air injector. Just something else to add to the list I suppose. I'm going to reach out to them tomorrow and will post an update once they get back to me.

Doug Thorley warranty excludes rusting "stainless steel" headers caused by weather. Then, what the hell else causes rust other than weather? Maybe you should tell them it was the carwash that rusted their headers. Crap product from a crap company.

All the Doug Thorley apologists seem to be late to this thread for some reason.

Looking at the photos, it looks like the ceramic coating is coming off and some surface rust has happened... Nothing that affects the performance of the headers.

In marfys thread, the issue was the secondary air injection tubes were made of mild steel and not stainless and DT admitted as much and fixed it moving forward.

Your primaries are stainless and should last a very long time.

What you're seeing wouldn't concern me much other than it not looking good, but the rust doesn't appear to be significant... Keep an eye on it to see how fast it progresses over time.

Come back this time next year and let's have a look.

I too am in NJ and love my Headers, Y Pipe, with the Gibson cat back exhaust! My Gibson cat back exhaust is supposedly stainless as well and it rusted after a few months. It does appear to be only surface level rust and does not concern me much. I will have to monitor my Headers and see where they are a year from now.

Dealing with CEL 0420/0430 codes for now, thinking I need to remove the upstream bung extender and only use the down stream bungs.

So yah, those don’t look like mine looked when I started my battle to get things sorted with Doug Thorley. I agree with others that it almost looks like the ceramic coating is somehow rusting…

On the other hand, it’s weird a stainless steel product is rusting at all. I’d keep asking the company why that is. It’s a shame their customer service hasn’t improved at all. How hard is it to spend 10 minutes with a customer reviewing their concern?!? I guess it would depend how many they get a day….

In other news, I sold my truck and bought a Volvo XC90. I know, different world completely. So, I may not be here to often but I will chime in if I can.

My theory is carbon steel grinding dust wasn't washed off well before coating. It shouldn't rust all the way through if it is indeed SS construction, so what you see is just a coating blemish/failure.

Again just my theory.

Either that or carbon steel dust settled on it after install and 'baked' into the ceramic coating and started to rust...

triethylborane said:

Stainless steel alloys have different properties including corrosion resistance. Pricing is a key factor in the alloy used by the mfg. No apology, I dont have a V8 and dont care about Doug Thorley.

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Good point, we don't really know what grade of stainless they used. We could only hope 304, but probably 409 or cheaper. 409 can get surface rust, and a magnet sticks to it, but not 304.

I'm not the metallurgy expert really, but my initial thought is also a low grade of stainless so they can call it stainless but it keeps costs down. If theres one thing I've learned about engineering/manufacturing, its that companies are always trying to drive down costs while, unfortunately, testing the quality limits

Embeded pics for the lazy like me lol:

Inv4drZm said:

Good point, we don't really know what grade of stainless they used. We could only hope 304, but probably 409 or cheaper. 409 can get surface rust, and a magnet sticks to it, but not 304.

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I was going to edit with some of the alloy info you provided, but tabbed and accidentally deleted and too lazy to repost since you quoted it anyway. I would guess 409 from the pictures and price.

y=mx+b said:

I'm not the metallurgy expert really, but my initial thought is also a low grade of stainless so they can call it stainless but it keeps costs down. If theres one thing I've learned about engineering/manufacturing, its that companies are always trying to drive down costs while, unfortunately, testing the quality limits

Embeded pics for the lazy like me lol:

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Thanky you for posting this! I tried uploading them originally and it failed to do so the first time. I wish they were up forward with what kind of ss they sued. would have made purchasing them much easier.

KrazedJD said:

I too am in NJ and love my Headers, Y Pipe, with the Gibson cat back exhaust! My Gibson cat back exhaust is supposedly stainless as well and it rusted after a few months. It does appear to be only surface level rust and does not concern me much. I will have to monitor my Headers and see where they are a year from now.

Dealing with CEL 0420/0430 codes for now, thinking I need to remove the upstream bung extender and only use the down stream bungs.

Click to expand...

I almost have the same setup! accept I'm running a Magnaflow cat-back. or was. Removed that entirely and am currently listening to the V8 in all of its glory. still have cats ofc but it still sounds amazing. did you get the message that I sent you? want to make sure that it went through

I just wish DT would offer an option with the cats attached. The installation is a pain but I could probably do it. Welding the cats not so much.

Someone should build a jig and weld up a bunch to sell on the forum lol.

Lucas606 said:

I almost have the same setup! accept I'm running a Magnaflow cat-back. or was. Removed that entirely and am currently listening to the V8 in all of its glory. still have cats ofc but it still sounds amazing. did you get the message that I sent you? want to make sure that it went through

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No I don't see a private message from you, but am interested in your solution. Running without cats sure does sound nice, reminds me of what trucks used to or should sound like!

That's not the headers "rusting out". That's certainly not structural damage... yet.

Stainless Steel is as such, "stain less" because it arrives "pre-rusted". Referring to it's chromium oxide layer (as opposed to iron oxide, which is brown). Chromium oxide is most often clear on well finished surfaces exposed to oxygen on the stainless. Sometimes it can appear white on surfaces that have damaged finish or have suffered acid attack.

Anyway, I'm pulling from long-long-long term memory here, as I took metallergy in school 16 years ago, stainless can rust brown. It still has iron in it and therefore can get brown rust forming on it. This damage could also be grinding cast off of normal iron that wasn't washed prior to coating, as Inv4drZm pointed out.

I found this article which might help with some of the more specific technical explainations:
Remove Rust From Stainless Steel And How to Stop it From Coming Back

Given that it's an exhaust system, it may be difficult to maintain any kind of coating not specifically designed for super high heat. And obviously applying any new coating directly is going to be very difficult given the inaccessibility of most of the headers surface. If you are able to dissolve the brown rust as described in the linked article, I'd imagine it wouldn't be hard to get the original stainless finish back from there with some research and a little know-how. Stainless is very resilient, as the name implies.

As others have mentioned... it'll be more relevant to see the corrosion situation as it develops in 1-5 years from now. If it remains a surface finish problem... well, it's not a show truck anyway. Should it show pitting and measurable loss of material mass, that's an entirely different issue altogether.

I don't see anything there that would make me panic and start pulling the DT-shorties out, thinking they'll turn to into brown dust before the piston rings are worn to a nub.

It's metal... it's outside... and specifically, this metal gets SUPER HOT, then cold... THEN SUPER FRICKIN' HOT... then cold. Over and over and over and ov... you get my point. Which is some of the most difficult conditions a metal can experience to maintain excellent surface finish.

I guess the best way to do is get fully titanium headers, problem solved.

:typing: for comparison..

My understanding that headers for the boating industry is made of Stainless Steel 316L .. the saltwater marine environment is harsh, to say the least..

Marine Exhaust Systems, Headers, Manifolds, Tips, Silencers and more!

Stainless steel 316L .

i have experienced exactly this same issue and was really disappointed i dropped all that coin to have it rust within a few weeks.

L8Shift said:

:typing: for comparison..

My understanding that headers for the boating industry is made of Stainless Steel 316L .. the saltwater marine environment is harsh, to say the least..

Marine Exhaust Systems, Headers, Manifolds, Tips, Silencers and more!

Stainless steel 316L .

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Yes, but $$. Had stainless manifolds on a mercruiser HP465, several thousand dollars.

awhitney1 said:

I guess the best way to do is get fully titanium headers, problem solved.

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That or iconel, but $$$$.

gimlithepirate said:

I just wish DT would offer an option with the cats attached. The installation is a pain but I could probably do it. Welding the cats not so much.

Someone should build a jig and weld up a bunch to sell on the forum lol.

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I had a disappointing conversation with a shop in CO today, where they refused to install my DT long tubes. They told me it was illegal to move the cats and as far as the short tubes go, it is illegal to not use the OEM cats from the OEM headers - something about engine codes matching. Anyway, this may be why this isn't an attractive option. If aftermarket cats are illegal, nobody it going to pay the money to scavenge cats from OEM headers and weld them into the DT shorties. I did ask if this was a "Colorado thing", as at least in Denver and a couple other counties, emissions have to be California compliant. I was told this was a federal thing. Suspect in my opinion.