Doug Thorley Headers for 4th gen V8, ** 1 day sale.

[Jason B]

Ok, cool. I'd prefer to buy everything at one place. Wait, do I have four cats too? Dang, thought it was only three.

" since you have to cut the factory ones out to do the install anyway"

Do you mean that people cut off their OEM cats and then re-weld them to the end of the DTs?

I am planning on replacing the Y pipe+cat piece from the unit from Magnaflow which seems to have a better 2 into 1 arrangement. Do you sell that Magnaflow Y pipe as well?

Correct. Yes, 2 up front and 2 further back. And yes, you have to cut out those front two cats and re-weld them to the new headers for install.

And yes, I sell that to, I can get just about any part these days. This is big purchase and most call over the phone to order because they have quote a few questions, but yes and my prices on magnaflow are good. Give me a ring or a text when you're ready 717-319-2100

 

[BrianSD_42]

For those of you guys that are hung up on dyno numbers you have to consider that the results are on a stock vehicle with no other modifications unless stated, this is also at sea level.

There is absolutely no way a stock 4th will see a 35HP gain by only adding aftermarket headers while still keeping the stock intake and stock exhaust.

To really gain anything significant out of this mod you would need to upgrade to a CAI and aftermarket high flow exhaust. No way around it.

I've got headers, exhaust and CAI. 35HP gain LMAO, yes I have a V6 but it doesn't matter. When K&N dyno'd the V6 3rd Gen with their CAI they found a ~7HP gain at wheels only on a truck that also has a modified exhaust to allow the larger airflow. The other truck dyno'd with a CAI but factory exhaust had a much smaller gain.

The point is just adding one thing isn't going change much and it certainly won't be 35HP even if you do all 3. Still I'm pretty jealous of you guys with 200+ HP at the wheels. Must be nice.

With all that said ..... Hey if it's a good deal then buy em.

 

[Marfy]

That sounds excellent.. if you can post up any picture of that hooking up.. it would be appreciated

Here you go

 

[Inv4drZm]

There is absolutely no way a stock 4th will see a 35HP gain by only adding aftermarket headers while still keeping the stock intake and stock exhaust.

To really gain anything significant out of this mod you would need to upgrade to a CAI and aftermarket high flow exhaust. No way around it.

I've got headers, exhaust and CAI. 35HP gain LMAO, yes I have a V6 but it doesn't matter. When K&N dyno'd the V6 3rd Gen with their CAI they found a ~7HP gain at wheels only on a truck that also has a modified exhaust to allow the larger airflow. The other truck dyno'd with a CAI but factory exhaust had a much smaller gain.

The point is just adding one thing isn't going change much and it certainly won't be 35HP even if you do all 3. Still I'm pretty jealous of you guys with 200+ HP at the wheels. Must be nice.

With all that said ..... Hey if it's a good deal then buy em.

To some extent I agree with you but...

This thread proves to me that 17hp can be gained with a CAI and exhaust alone, 8hp more with an air ratio tune.

With just the headers, the dyno showed +11hp and +18tq

Add the two together (if it works like that) you get +36hp and similar torque gains. Maybe more with the tune working with the headers. Replace the incredibly restrictive Y pipe and remove a couple cats: +5 more hp?

So at least 245 awhp and 290 awtq naturally aspirated.

Throw in the URD supercharger at 5 psi boost you get +100hp and +100tq from stock. 345 awhp and 390 awtq?

 

[Marfy]

For those of you guys that are hung up on dyno numbers you have to consider that the results are on a stock vehicle with no other modifications unless stated, this is also at sea level. I have a GX470 with Thorley Headers, Flowmaster High Flow Cats, aFE cat back exhaust and a Volant intake. According to the manufacturers I should be getting over 75- 80 HP, get real I'm in Colorado above 5000 feet it is no where near that but it runs a hell of alot better pulls harder and sounds mean as shit, but mellow when cruising the free way my MPG has increased slightly the power is much more and I'm happy with it. I also have 35 inch tires on it which definitely soaks up the increase. If all your worried about is the Dyno numbers to tell your friends, save your money but the results are real and will vary from vehicle to vehicle. They are also less expensive the OE manifolds if yours are cracked as many do.

+1

Well said.

To the dummies crying for dyno results: put up your own cash to install and get a dyno test.

I'm driving a big truck. I dunno what kind of gains I got with my headers, cat delete, exhaust, cai, and maf calibrator. Is it a Porsche now? No. Is it faster than your 4Runner, probably.

 

[HiLex]

I have added two rear O2 spacers to get rid of the CEL and it has passed emissions test twice with this setup.

 

[alia176]

Here you go

These are great pics. There should be two O2 sensors - the one before the Cat but on the headers (can't see them) are AFR sensors used by the ECU for fuel management. The second O2 sensor after the Cat is the O2 sensor for tripping P0420 and P0430. It's interesting that you aren't getting either of these two codes w/o sims. That's a head scratcher.

I'd like to look into the MAF calibrator. Is this an URD thing or from some other vendor?

 

[Jason B]

Here you go

Great pics! I'm also working with Gibson right now to get a custom Y pipe done for these trucks which will also save you guys a lot of money. It's a long process though.

Doug Thorley 03-04 headers

Doug Thorley 05-09 headers

Also, the Gibson catback, which pairs great with these headers.

Gibson 4th Gen exhaust

I can do any and all DT headers at a deal, not just these, just call or text 717-319-2100 for anymore questions.

 

[blackoutt]

These are great pics. There should be two O2 sensors - the one before the Cat but on the headers (can't see them) are AFR sensors used by the ECU for fuel management. The second O2 sensor after the Cat is the O2 sensor for tripping P0420 and P0430. It's interesting that you aren't getting either of these two codes w/o sims. That's a head scratcher.

Not really, he's got cats welded in before the rear O2 sensors so they are still reading close enough to not trip a fault.

Mine with no cats before the rear O2's will log a 420 and 430 everytime until I put 3 spacers on each O2 sensor.

 

[alia176]

Not really, he's got cats welded in before the rear O2 sensors so they are still reading close enough to not trip a fault.

Mine with no cats before the rear O2's will log a 420 and 430 everytime until I put 3 spacers on each O2 sensor.

Thanks for the input. However, one of my point is that the front O2 sensor (aka AFR sensors) need to see the exhaust stream in it's "raw" state for adjusting the air/fuel mixture. So, I'm curious, if putting the AFR after the first set of cats is detrimental for the ECU. Again, just trying to learn not arguing/debating. This is good stuff.

 

[blackoutt]

Thanks for the input. However, one of my point is that the front O2 sensor (aka AFR sensors) need to see the exhaust stream in it's "raw" state for adjusting the air/fuel mixture. So, I'm curious, if putting the AFR after the first set of cats is detrimental for the ECU. Again, just trying to learn not arguing/debating. This is good stuff.

Front O2/AFR sensor bungs are in the DT headers so they WILL be ahead of the cats in the raw stream whether you add cats on or not after that is up to you. The rear O2's are only for "header catalyst" efficiency checks and have no impact on performance. It's the rear O2 that the URD emulator plugs into so that you don't get faults for reassembling without upstream cats, or just space them out of the stream. There is also on my 4r two more catalysts behind the rear O2's (I think this was a 50 state emissions version) there is nothing to monitor their performance or presence.

 

[SAC-CA-Runner]

So not sure anyone will read this post so I may create one, but has ANYONE made a template to weld on the cats to the headers? My truck is currently down in my garage and can't be moved to a shop to have them test fit, weld, test fit, weld. However I'm pulling the heads as I think my engine blew up after my radiator got plugged (separate post). So if I'm pulling them, I'm getting these headers. I'm in CA, but I'll "find" a shop to smog it. But would be nice to get them shipped to someone somewhere that has already made a template to weld these up and fit off the bat.

 

[blackoutt]

So not sure anyone will read this post so I may create one, but has ANYONE made a template to weld on the cats to the headers? My truck is currently down in my garage and can't be moved to a shop to have them test fit, weld, test fit, weld. However I'm pulling the heads as I think my engine blew up after my radiator got plugged (separate post). So if I'm pulling them, I'm getting these headers. I'm in CA, but I'll "find" a shop to smog it. But would be nice to get them shipped to someone somewhere that has already made a template to weld these up and fit off the bat.

I built some wooden jigs off of a spare set of stock manifolds and it worked well. I sent them off to JeepWinch with the manifolds so he could do the same. Maybe see if he'll ship them to you or just build a set off of your stock manifolds while the engines apart.

Here's what I did

post2609011

There's a few guys in this thread that did the same idea, trashcatmotorsports and jagerzel.

http://www.toyota-4runner.org/4th-gen-t4rs/108131-interest-custom-built-4th-gen-v8-4-7-doug-thorley-headers-55.html

 

[SAC-CA-Runner]

HAHAHA...I was looking for those posts and figured they were in a different post. Little did I know there were buried here! Sheesh. I wonder what cats most are using? Flowmaster or Magnaflow. I'll be building me some jigs for sure.

I built some wooden jigs off of a spare set of stock manifolds and it worked well. I sent them off to JeepWinch with the manifolds so he could do the same. Maybe see if he'll ship them to you or just build a set off of your stock manifolds while the engines apart.

Here's what I did

post2609011

There's a few guys in this thread that did the same idea, trashcatmotorsports and jagerzel.

http://www.toyota-4runner.org/4th-gen-t4rs/108131-interest-custom-built-4th-gen-v8-4-7-doug-thorley-headers-55.html

 

[SAC-CA-Runner]

Ends Aug 4th! V8 4th gens are known to get a leaky cracked header and start making a ticking sound. These new headers fix that problem, add abotu 2-3 more MPG and aprox 35 HP gain. New Toyota headers are DOUBLE the price. Get in while you can.

Doug Thorley 03-04 headers

Doug Thorley 05-09 headers

Also, the Gibson catback, which pairs great with these headers.

Gibson 4th Gen exhaust

I can do any and all DT headers at a deal, not just these, just call or text 717-319-2100 for anymore questions.

Left you a message...still got these? I know not at this price...but looking for a setup and want to chat. Thanks

 

[aznxfactor]

still available?

 

[Jason B]

still available?

BACK, IN STOCK, if anyone wants these ORDER soon, when they go out of stock, it's 3-4 weeks easy.

Doug Thorley 03-04 headers 3in stock!

Doug Thorley 05-09 headers 3 in stock, order soon, these go fast, then it's 5+ weeks for more.

Also, the Gibson catback, which pairs great with these headers.

Gibson 4th Gen exhaust

I can do any and all DT headers at a deal, not just these, just call or text 717-319-2100 for anymore questions.

 

[kyle_pc_75]

Can't wait to make this mod. Stupid cracked manifold makes me sound SO ghetto. Thanks DT.

 

[Jack Gallivan]

Can I get Doug Thorley headers for the V6 in a 4th gen? Also, what exhaust setup should I run? I'm looking at the dual tip Magnaflow that exits behind the passenger side rear tire Please let me know. Thanks!

_________________
2004 SR5 4WD V6
3 inch ICON Stage 1 Lift Kit, 285/70R17 Cooper Discoverer S/T Maxx, 17x8 Stealth Custom Series Stealth 6 wheels in matte dark bronze

 

[Dahgoose]

The install was not fun!! That being said, the DT headers are a quality built product, everything, including the air injection tubes lined right up.

The 4Runner feels a lighter when accelerating and around town I am up 1.25 mpg. I have yet to test the freeway mileage.

Thanks JasonB for setting me up, I'm hoping the Carb #'s will be available soon!