Doug Thorley headers installed! (95.5 v6)

Hey guys!

Well, last week I had a set of Doug Thorley headers installed on my 95.5 Tacoma v6 4x4 5-speed manual.

Prior to these headers, my performance mods:
- "velocity stack mod" (deckplate mod but using a 4" Blox Racing velocity stack---search for my username if you're curious)
- Airaid intake tube w/Airaid replacement K&N-style panel filter
- custom in/out 2.5" catback(technically, all custom piping from the downstream o2 sensor to the tip) w/Magnaflow center in/offset out 18" muffler

My tacoma is a Federal spec truck(1st owner bought it brand new in Hawaii) which means no EGR + 1 cat.

Bought the non-EGR version of the Thorley headers from URD(great service!). CARB legal!

BUILD QUALITY:
No surprises here, simply awesome. Thick flanges & solid welds. The chrome ceramic coating makes my relatively clean engine bay look filthy haha.

PERFORMANCE "FEEL:"
Mind you, I wasn't expecting a huge gain, but it's definitely noticeable....and nice! Rowing through the gears seems to take much less effort for "around the town" kind of driving. Romping on it, 3.5k-redline is where I feel the definite POSITIVE change in power. Regardless of your driving style, you'll surely FEEL a change somewhere in the powerband. Are these headers worth that extra 'umph'??? That's your call. I bought them, and I'm satisfied given my expectations. Gains are exponential with a supercharger I'd imagine.( ahhhh, maybe one day )

OBSERVED MPG GAIN/LOSS:
Hard to guage this one. I might have a heavier foot now haha. Initial observations, nothing to report. Lol. My mileage seems unaffected, but I'll update in a few weeks when my header infatuation dies down on the go pedal.

SOUND:
I think I nailed my goal with the exhaust sound. Tone & volume at idle remains unchanged. With my 18" Magnaflow, the tone is on the deeper side of "throaty" when putting the engine under load. At WOT, it roars and not ricey! It's definitely louder, but not annoying. ZERO DRONE. I can't make that up. Videos will be posted sometime, I am definitely lagging on vids!

FITMENT[per my exhaust shop guy]:
Both the driver and passenger side headers fit AWESOME.
*HOWEVER,* I'm not sure if I got a "Monday" crosspipe (lol) but mine was unfortunately jigged almost 3/4" too wide!! Can you believe that? Yikes! The exhaust guy, who's installed plenty aftermarket 3.4/4.0 Tacoma v6 headers, said he's never has this problem with Thorleys. He was on the phone numerous times with Thorley to try to figure out a this seemingly one-off problem, but no luck. Finally, he decided the best solution would be to cut the crosspipe in the middle, expand one of ends, and create a slip joint so he could get the perfect length then tack it, and ultimately weld it. You will see in the pictures. It turned out great after he applied his fix. Other than the crosspipe, these headers fit great with good clearances.

INSTALL NOTES:
- "these 3.4 headers are notoriously the fucking hardest set to install, without a doubt" -my exhaust guy lol.
- I wouldn't recommend Oem Toyota header gaskets, unless you're willing to machine out the rivets. Due to the 1 piece flange design, the headers will not seal properly if the rivets are not removed. The exhaust guy conveniently had machined 5VZFE 3.4 v6 header templates to cut out Percy Carbon XX gaskets for my headers. Google them, probably one of the best kinds of gaskets to use on aftermarket headers.
- Depending on what you're willing to do to make them fit, replacing the manifold studs is one of those "you're already there, might as well do it" kind of things.
- Because 95.5-04 FED/CA spec 3.4 v6 Tacomas had numerous variations on their exhaust systems, Thorley supplies a weldable flange to connect the collector to your factory cat pipe. You may luck out and not need this flange. In my application, the flange was welded to my cat pipe. Probably the easiest part of this install lol.
- If possible, definitely change the upstream(pre-cat) o2 sensor! URD has a helpful Denso sensor guide on their website so you get the right one.
- did I mention how much of a PITA these are to install? lol

Without anymore delay, PICS!

Driver side:




Passenger side:




Modified crosspipe:




Hope you guys find this helpful!

-Matt

 

I believe CA spec 3.4 Tacomas have EGR, but dont quote me.

 

Good to know!

 

This is what im thinking about doing next. But im looking at $300 i really would like to save. Maybe one day.

 

are those the shorty or the long tube, not sure if you had mentioned it in the write-up.
good job, i could very well believe how big a pain it could be, but they look sweet, and I am sure with the manga-flow exhaust they have a great sound. the other real good thing about manga-flow is they last. I put them on my stang in 2004 and when we parted ways in 2011 it still sounded great, and looked pretty good considering the the last 3 winters. salt hell

 

video?

 

Depending on your wrenching ability, the total expense could be much higher than just the price of these headers if you pay a shop to install them, as I did haha.

These are the shorty tubes. Unfortunately, long tube aftermarket headers for the 5VZFE 3.4 v6 are a "unicorn" part. They don't exist in the aftermarket unless you have some made. The 4.0 v6's get all the cool aftermarket headers. Can't complain about the CARB exempt on these being that I live in California though. LOVE my Magnaflow! All my vehicles I've changed exhaust systems on have been outfitted with a Magnaflow muffler. Definitely built tough!

Workin on it. I'm either busy or the weather decides to take a crap on me when I'm not! I will try to post one asap!


Matt

 

well shorty's are best for our engines. just like the overhead cam 4.6, not alot of grunt off the line, with this it helps with that, with long tubes you will be revving all day. yeah 300 dollars for headers... try 5000.00 with all a had done. one thinig that is not aroound for the trucks, I put in a MdI high performance coils, and they made a world of differance in the car. very smooth idle, i dont know but it helpes. its funny toyota uses 3 coils ford uses 8 and still has problems.

now start building that baby up and slide a supercharge in there.

 

Is there a difference in power?

 

*sigh* one day an s/c will make its way in there I hope!

Definitely. Not a crazy huge difference but it's very noticeable at the higher RPM's. Passing on the fwy in 5th gear takes less effort as well.


Matt

 

Nice, I am definitely purchasing these now. These probably not go on the truck for awhile though... I will put them on the new motor.

 

Nice write-up!

 

Why does thorley offer up ones with and without EGR?

 

For the 4runner applications.

 

I see you have since sold this, but. Do you recall if you had any difference in mpg's? Im getting ready to finally installing my jba headers and wondering if I'm going to lose some mileage

 

Because some Tacoma trucks like mine came with an EGR

 

Fake news, not true.

 

7 year follow up.