Doug Thorley 2.7 Headers

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:

 

Been considering this because passing on the hiway and on ramps suck with the 2.7. My question is how the hell were you getting avg 22 mpg? I usually get around 18 and best is 20. I have flowmaster and K&N drop in. Maybe its my tires. They are 265/65-17 and im curious as to what size your are. Anyway, good write up dude!

 

I drive like an old man! I was getting closer to 24 on the stock 16" Dunlop 245/75, but with larger 265/70 Michelin defender LTX, mpg went down to 22.5.

 

Wtf, I'm doing 15-17 average. I know I drive fast, but shit that's a big difference.

 

Mostly freeway driving. Round town stop and go I get about 20.

 

I found similar results when I install my header. My gas mileage also increase to around 24mpg. If you want another improvement remove the large snorkel in the passenger fender well. The air inlet opening is quite small compared to the rest of the intake. Also adding a better flowing muffler also helped. I'm running a Quiet Flow muffler shock is only slightly louder than the stock muffler.

 

Thank you for the advice on making it fit... I installed the header Friday and it has made a little difference also added Flowmaster did the secondary filter delete and resonator delete with high flow filter...

 

My LCE headers passed smog..???


EDIT: To be clear, I lived in Cali when I installed it.

 

There are no gains removing the secondary filter.

 

The trac light and check engine light just came on...

NOT HAPPY

 

Code was P2441 the air valve that sits above the header getting stuck...
I took it apart and see nothing wrong so cleaned and reassembled it
Drove for 100+ miles no more check engine light...
Went up to Palomar Mountain and it pulls harder going up hills....

 

Glad to hear the code cleared!!

 

I cleared it with the code reader but it has not returned (so far)....

 

Code came back today

 

Driving 65 makes a ginormous difference than driving 70-75. Also how you accelerate makes a difference as well.

 

Crap

 

Code came on as soon as i started the truck this morning after i cleared it yesterday..

I see on other forums that the weld around the air injection ports may be preventing a gasket seal...
I have emailed Doug Thorley and waiting to hear from them.

I had removed the secondary filter form a stock airbox I got on line, also modified the air inlet to the box and removed the baffle in the fender well...
I am going to reinstall the stock airbox to see if that keeps the code from returning.

If it still returns I will have no choice but to remove the header too look at the gasket and welds...

Yesterday I cleaned the MAF and throttle body (not that dirty)...

 

Code was pending this morning... again P2441 (Monday Labor Day) This was with the stock intake...

I took the air injection valve off and took the valve assembly apart.

Tried removing the screws that hold the reed valve assembly to the valve body and the screws broke off!! I was able to get one out with no trouble but had to drill out the second one...
Needed to retap the screw hole with a larger screw now 8-40 instead of 6-40.. (had some screws that I use to mount scopes to guns)
I turned the reed over and it sealed better (needed to use dremel to widen the hole so that it fit), so reassembled the valve..

I had previously removed the filter inside the air pump and added a little K&N style filter over the snorkel..
https://www.tacomaworld.com/threads/uni-filter-mod-on-2-7.489348/

I reinstalled my modified intake (Afe dry filter, secondary filter removed & some cutting inside the box) there is a definite power increase over the stock intake..

Checked for code after cold start (Tuesday) no code or pending code.... As I said:
If it still returns I will have no choice but to remove the header too look at the gasket and welds...

Will update if it changes....

 

If it comes back, you should look into the LCE header

 

I would have installed the LCE header BUT I live in the Peoples Republic of Kalifornia... So any "long term" Mod needs to be CARB compliant or reversible for smog testing