Headers for 1st Gen Tacoma with EGR Valve

Hello! I'm hoping to start a discussion about headers for my 2002 Toyota Tacoma. Here are some brief details about my truck:

• Engine: 4 cylinder, 2.7l with EGR
• Stock Exhaust Manifold
• Stock Catalytic Converters (Primary and Secondary)

Problem: Error Code P0420
Solution: I am replacing my exhaust manifold and catalytic converters (set in stone)

Question/Discussion: I am having difficulties deciding on a set of headers for my truck. I am aware headers will allow my truck to breathe and perform efficiently. However, the only set of headers I find are by Doug Thorley. Unfortunately, LCEngineering does not have a set of headers made for my truck with the EGR valve and with the dual port set-up (the area where the primary catalytic converter bolts to the manifold. Others with single catalytic converters have that "Y" shape port) May I have some input on the Doug Thorley headers? Are they obnoxiously loud? To include, I am replacing the catalytic converters with Magnaflow Direct Fit (#51869 and #51453) Thank you!

Goal: I only want for my truck to run efficiently. I don't want it to be crazy loud. Thank you for reading! I hope I was clear.

 

@Green_Machine4x4

OEM Mini Headers from a newer gen which I have on my 1995 4x4 2.7 manual.

Toyota 17141-75080

Will mate up to stock down pipe and has the EGR pipe port.

https://www.toyotapartsdeal.com/oem/toyota~manifold~exhaust~17141-75080.html

under 200 bucks OEM.

 

I have the Doug Thorly tri Y headers on my 1999 2.7 single cat and they are not any louder than stock to be honest. They do leak all the time and than they get loud and it sucks and is anoying. Also there is a secondary piece that they provide at least for my year truck that bolts in between the header and the cat that has the spot for the upstream O2 sensor and it runs against my transmission lines. Called Doug thorly and they refuse to do anything to fix it and say that it should fit and that's all they can say/do about it.

All in all I'm not too happy with them if that helps you feel better about not getting them lol

 

Where do they leak from?

 

From the #4 cylinder exhaust port where there is no bolt in the far corner. The bolts always loosen up and need to be retightened. The stock metallic gaskets don't make a good seal on the header since the exhaust port is oval and the header is a larger round mating surface.

Also the intermediate pipe that bolt in between the header and cat where the o2 sensor goes always leaks. I had to drill the nuts and bolt heads and safety wire them so they didn't back out from vibration.

 

That sucks - so the stock manifold didn't have an issue without a bolt holding it in that corner?

I just installed some dt headers on my 3.4 with oem gaskets and permatex copper rtv between both sides of the gasket.

Thread locker won't keep the bolts from backing out?

 

I'm not a big fan of thread locker on the block. and it wont work on just the nuts because the studs the header mounts on threads in also and backs out as well. The nuts are lock nuts and mine I'm sure have lost their locking ability and need replacing so that is my next option next time.
And I had no issues with the stock manifold leaking.

My Doug thorleys fit so poorly that the header is preloaded just to get alignment to my cat. That preload is constantly applying pressure on the header in that corner away from the engine so during heat cycles I'm sure that is a root cause of the constant leak and possible warping of my header.

You may have no issue just re torque the nuts after a few heat cycles and if the nuts are still locking like they should yours might just be ok.

Exhaust leaks are really comin with aftermarket headers of any kind though.

 

I've had a cheap ass pacesetter on my 97 for over 3 years now and outside of the crap gaskets it came with its been fine

 

Thank you for the responses. I hear so many mixed reviews about Doug Thorley and I'm wondering if it may be wise to simply replace the manifold and add a cold air intake to breathe better as well as keep it a little quieter than it would be with a header added. I'm aware the cold air intake may sound different, but in my mindset, if I have the manifold replaced, then I shouldn't have to worry about aggressive sounds or leaks of any kind? I may need to research a bit more!

 

I believe I found something just like this on PartsGeek.com as well! They look identical!

 

Yup looks like that's actually OEM for your truck. Older years had an actual manifold (cast) which was notorious for cracking. Thought that is what you were referring to when you said manifold. Mine cracked twice. I will say that OEM engine mounts are a must. I had soft mounts which were aftermarket and that was the issue. Engine swayed too much putting extra pressure on the manifold. Replaced to the mini headers and OEM mounts problem solved.

 

I wish I had gone with this one now, cheaper and better but I thought Doug thorley was quality. It's a nice header I'm sure if it had fit though

 

i might have to pick up one of these manifolds. my exhaust is sounding worse by the day

 

That's what I have in my 95 2.7 4x4. direct fit.

 

Thank y'all lots for the input! So to recap, the manifold/mini header displayed on PartsGeek.com is a direct fit replacement and you have had no issues whatsoever? I've never used PartsGeek.com but y'all are on top of everything and that's awesome! I only wonder what the difference is between this and the Doug Thorley headers? From the one on PartsGeek.com, has rust been an issue either?

 

The shorty header people are talkin about is a factory toyota part. The later years of the 3rz yota dumped the cast manifold for the tubular shorty header. I wouldn't be to worried about fitment issues.

 

It's cheaper from the link I sent and it's OEM. Idk about the one parts geek is selling

 

Would this fit my 1999 2.4 tacoma and how is the performance? as you can see I might have a crack on my manifold
Thanks



It states that if doesn't fit my 1999
Making sure it will. https://www.toyotapartsdeal.com/oem...1=2RZFE;5=ATM;6=4HC)&Location=manifold,,17141 This states that it will but not sure if it's the same material

 

So I'm not 100% that the 2.4 is the same manifold as the 2.7. I can look into it for you. The mini header I linked there was for a 2.7 but if the manifold is the same then I don't see why it wouldn't fit. I mean the site also says it will not fit my 1995 2.7 but it was direct fit. Reason it says it won't fit for me is because those didn't exist back then for the 2.7 so the OEM part number is cast iron.

 

Please do thanks!