Doug Thorley 2.7 Headers

MrCrowntown · Sep 5, 2017

That's where I installed mine, and I had no issues at all. 3 years in california with it on, no issues anywhere with visual or actual emissions testing.

I do hope you find a fix for your header. All bs aside, I just wish the best for everyone, and your thought about checking out the flange is a good start at this point.

JohnGee · Sep 5, 2017

WOW! I would like That!! if I can not fix the CEL I may swap it out......

Thecsoup · Sep 16, 2019

Gusfco[OP] initial post: ↑

My rig: 2013 DCSB 2.7, auto,
265/70 r16, scangauge II,
Afe dry filter, secondary filter removed, magnaflow muffler.

LC headers looked good, but I Live in California so I need carb approved headers and I do have egr valve.

Installed Doug Thorley tri-y part# THY-509Y-C a few weeks back. Website says for 2005-2015 2.7. Bought from AutoAnything on sale + extra discount for $377.88 total with free shipping. Great welds. Finish is shiny, but not chrome.

Install was a PITA. Took me 3 hours total, and I am an experienced mechanic. Instructions were basic, but didn't really need them. Make sure to remove ground from battery. Remove air filter box and pipe along with anything in the way.
Removal of stock header was easy. Reused the stock gasket and stock hardware. It's more of a metal sheet gasket, so I cleaned it and reused. No issues there.
Donut gasket on the downpipe reused too. No issues either.

Now the fun part. The egr housing bolts directly to the head and it was very close to the stock exhaust. The DT's have a little larger pipes and flange, so they hit. There was no play there so the install was put on hold. I contemplated for a few minutes and figured the egr housing could move or shift up a little with some grinding of the bottom housing OR just enlarge the 2 holes on the unit that mounts to the engine. I used a 3/8" bit and that gave enough play so both the egr unit and headers no longer touch. Enlarging the mount holes did not do anything to damage anything so problem solved!

After that, bolted everything up and took a test drive and checked for leaks. No leaks, no problems.

Initial test drive, noticed no difference at all. I felt like I wasted my time and money, but knew I had to do some gas fillups for the computer to adjust. After a few fillups and the computer adjusted, now it performs much better. At a dead stop, pull is much improved (slightly but still better ) but on the freeway is where it shines. Getting on the freeway and passing is much easier and pedal feels a lot more responsive. I'm not smashing the pedal, but driving like I normally do. Hills were always an issue before but now my gutless 4cyl is much improved. Don't expect 6cyl performance or screeching tires. I loved my taco before the headers and after I'm loving her more now.

My mpg prior was 22.5 average for past 4 years. Use my scangauge II to confirm. Mostly freeway driving 5-80mph (Socal freeways!) Mostly flat with some mild inclines. Now 22-24 mpg. Same driving habits but I feel like I don't have to stomp the pedal to get to freeway speed or keep up with traffic flow. Engine breathes much better and more responsive. Didn't get any louder.

I was contemplating doing this for several months, maybe years, but I'm glad I did.
Thanks for all the great reviews tacomaworld. Thought I'd contribute with my experience and I hope it helps anyone thinking about doing this too.

Stock:

Installed without airbox:

Comparison:

Click to expand...

Hey man I'm just about to install these and the install instructions states to use high temp bead of silicon , did you use that or did you find a gasket for it

taco4pot · Jun 1, 2022

JohnGee said: ↑

WOW! I would like That!! if I can not fix the CEL I may swap it out......
Click to expand...

I hate to bring these old posts back from the dead, BUT..... did you ever figure out what was causing the p2441? I installed my DT header about a month go and I am throwing that pending code every other day. I hate to have to scrap that header.

Log in or Sign up

Welcome to Tacoma World!

Doug Thorley 2.7 Headers

#21
MrCrowntown Well-Known Member

#22
JohnGee Member

#23
Thecsoup New Member

#24
taco4pot Member

Products Discussed in

Log in or Sign up

Useful Searches

Welcome to Tacoma World!

Doug Thorley 2.7 Headers

#21 MrCrowntown Well-Known Member

#22 JohnGee Member

#23 Thecsoup New Member

#24 taco4pot Member

Products Discussed in Entire Site Forum: Performance and Tuning

#21
MrCrowntown Well-Known Member

#22
JohnGee Member

#23
Thecsoup New Member

#24
taco4pot Member

Products Discussed in