Are they worth the $$$

[0verland]

I've been doing a bit of research however I haven't found a definitive answer.

What are the expected gains from the Doug Thorley headers on the V8 and are they worth the cost? I see most people end up getting them as a cheaper alternative to replacing cracked stock headers, but is that the only good reason? My car has been in Arizona its entire life so no real exposure to corrosive weather conditions, so I can only expect that the headers will last unless they crack from the heat of extended use?

On another note, what about the UDR Y-Pipe? Is this something to even consider? I currently have a Gibson side exit cat-back exhaust and I am looking for more gains.

Really I just want to know if I have reached the peak of the performance of the V8 without spending a boatload of money and If I should just continue down the list of mods to doing suspension work, etc.

Any insight would be greatly appreciated.

 

[Keros]

Having recently installed the DT Headers on my '05, I hope I can provide some input here:

Setup is now Doug Thorley headers (with the air injection pipes), with an injection disable module. Into magnaflow high-flow cats, retaining all 4 original O2 sensors. Then cross over pipe is all custom, merging into a single pipe to enter the dirty deeds resonator.

I retained the tailpipe section because it's all mandrel bends and I had run out of fabrication time (needed the truck for a two week trip), as that the headers took alot longer than the fabricator anticipated (Rusty Alberta truck).

The truck has noticeably more power. Climbing mountain passes, she no longer gear hunts to maintain speed... the ol' girl just seems to know what she wants to powers up the hills. The truck felt solid before but now it feels like driving a battering ram that thinks it's a missile.

There's two big downsides:

#1 - Torque

All that gorgeous low end torque evaporated. Now mind you, on the stock configuration, the torque buildup is almost a vertical wall, climbing from 2000rpm to 200ft-lbs at 2200rpm, give or take. Then peaking around 3500-4000rpm to 234ft-lbs. Essentially the torque curve is not a curve, it's an upside down U shape. Which is wonderful for a truck. Not so great for a "sporty" feel. Anyway, after the exhaust kit install, I can only estimate that the torque curve is now a curve (and not a near vertical wall)... I haven't had a chance to take it back to the dyno.

Realistically, it just doesn't snap your head back into the seats when you give it a tiny bit of jam when you get her moving anymore. Your head now rolls back with the torque building. Before it was like "BAM! TORQUE MOFO!" Now it's more like... "Mmm, feel that torque coming on!"... More like a dining room dimmer switch than a light switch now.

With peak power (very likely) being higher, I'll take the rocket ship ride over the instant-on torque, though.

#2 - Premium Fuel

Runs like utter shit on 87 octane. This came up when I picked up the truck, the guys at the shop that did the install (having done a few 2UZ-FE exhaust systems), warned me that the free flowing exhaust will likely cause the ECU to pull all kinds of timing, and 91 or 94 octane will be required. Well, I tried a tank of 87 and the truck sounded terrible, hesitated, lacked power... etc. So, begrudgingly I returned and paid tribute to the Car Gods for my sins. Been $100 fills ever since.

Honestly, I'd rather have the money in the bank than the sweet exhaust. The truck goes like stink, sounds badass (big thanks to Dirty Deeds' BA Mufflers for that). I just couldn't take the tin-can ticking of the cracked headers anymore.

Atleast now it sounds like a real V8.

It wears the Toyota badge with pride.

For the power gains it was not worth it, and I wouldn't have done it for that alone. For sanity sake and self respect... well, you can't put a price on that.

EDIT: Before someone starts flaming my dyno numbers, remember that my wheels weigh 100lbs each, not the weeny stock wheels and OEM P-type tires. The calculated losses induced by extra unsprung rotating mass decently approximate the stock power numbers... for a truck with 270000km.

 

[Billynath1988]

Having recently installed the DT Headers on my '05, I hope I can provide some input here:

Setup is now Doug Thorley headers (with the air injection pipes), with an injection disable module. Into magnaflow high-flow cats, retaining all 4 original O2 sensors. Then cross over pipe is all custom, merging into a single pipe to enter the dirty deeds resonator.

I retained the tailpipe section because it's all mandrel bends and I had run out of fabrication time (needed the truck for a two week trip), as that the headers took alot longer than the fabricator anticipated (Rusty Alberta truck).

The truck has noticeably more power. Climbing mountain passes, she no longer gear hunts to maintain speed... the ol' girl just seems to know what she wants to powers up the hills. The truck felt solid before but now it feels like driving a battering ram that thinks it's a missile.

There's two big downsides:

#1 - Torque

All that gorgeous low end torque evaporated. Now mind you, on the stock configuration, the torque buildup is almost a vertical wall, climbing from 2000rpm to 200ft-lbs at 2200rpm, give or take. Then peaking around 3500-4000rpm to 234ft-lbs. Essentially the torque curve is not a curve, it's an upside down U shape. Which is wonderful for a truck. Not so great for a "sporty" feel. Anyway, after the exhaust kit install, I can only estimate that the torque curve is now a curve (and not a near vertical wall)... I haven't had a chance to take it back to the dyno.

Realistically, it just doesn't snap your head back into the seats when you give it a tiny bit of jam when you get her moving anymore. Your head now rolls back with the torque building. Before it was like "BAM! TORQUE MOFO!" Now it's more like... "Mmm, feel that torque coming on!"... More like a dining room dimmer switch than a light switch now.

With peak power (very likely) being higher, I'll take the rocket ship ride over the instant-on torque, though.

#2 - Premium Fuel

Runs like utter shit on 87 octane. This came up when I picked up the truck, the guys at the shop that did the install (having done a few 2UZ-FE exhaust systems), warned me that the free flowing exhaust will likely cause the ECU to pull all kinds of timing, and 91 or 94 octane will be required. Well, I tried a tank of 87 and the truck sounded terrible, hesitated, lacked power... etc. So, begrudgingly I returned and paid tribute to the Car Gods for my sins. Been $100 fills ever since.

Honestly, I'd rather have the money in the bank than the sweet exhaust. The truck goes like stink, sounds badass (big thanks to Dirty Deeds' BA Mufflers for that). I just couldn't take the tin-can ticking of the cracked headers anymore.

Atleast now it sounds like a real V8.

It wears the Toyota badge with pride.

For the power gains it was not worth it, and I wouldn't have done it for that alone. For sanity sake and self respect... well, you can't put a price on that.

EDIT: Before someone starts flaming my dyno numbers, remember that my wheels weigh 100lbs each, not the weeny stock wheels and OEM P-type tires. The calculated losses induced by extra unsprung rotating mass decently approximate the stock power numbers... for a truck with 270000km.

Thats the best description ive read yet.. this topic should basically be closed.. lol

 

[blackoutt]

Cliff notes:

Do you want a little more power? And more sound? Fixing cracks and ticking? Buy them.

Do you want it to be a rocket ship/sports car? Not worth it.

 

[V8Limited4wd]

sprygsxr spent about $3k for parts, labor, and a tune to get ~250HP/376TQ at the crank. I'll be doing the same once I get the Magnaflow y-pipe, cats and O2 sensors. I'll be keeping my 4Runner for at least another 10 years so it's worth the investment.

DT header install

 

[0verland]

Honestly after hearing this I don't know that the DT headers or any headers for that matter are really worth it. What about the y-pipe? Any sense in going with that if you don't do headers? If not on to suspension work for me...

 

[Keros]

Honestly after hearing this I don't know that the DT headers or any headers for that matter are really worth it. What about the y-pipe? Any sense in going with that if you don't do headers? If not on to suspension work for me...

In my opinion, the y-pipe as a test-pipe style component that eliminates the catalytic converters is not a responsible thing to install. We talk about leaving no trace when we wheel, and trucking what we brought it, etc; but driving around without cats emits all sorts of chemicals that aren't good for the ozone layer or people's health.

It's a small thing, but a good set of high performance cats will make neglegable difference to the truck's performance.

Since the pre-cats (the ones right off the manifold) only operate for the first couple seconds, meh... those aren't as big of a deal.

Furthermore, apparently the 2UZ ECU is smarter than most people give it credit for. Sometimes they figure out that they're being tricked with a false O2 sensor signal and start throwing CELs. I know URD makes a signal module that lets you use their test pipe... but I think it may be easier and cheaper to just put cats in and keep the ECU happy. It's simpler and it's what Toyota intended.

EDIT: I think the test-pipe and the signal faker thing would have been around the same price as the custom fab work and cats.

 

[0verland]

In my opinion, the y-pipe as a test-pipe style component that eliminates the catalytic converters is not a responsible thing to install. We talk about leaving no trace when we wheel, and trucking what we brought it, etc; but driving around without cats emits all sorts of chemicals that aren't good for the ozone layer or people's health.

It's a small thing, but a good set of high performance cats will make neglegable difference to the truck's performance.

Since the pre-cats (the ones right off the manifold) only operate for the first couple seconds, meh... those aren't as big of a deal.

Furthermore, apparently the 2UZ ECU is smarter than most people give it credit for. Sometimes they figure out that they're being tricked with a false O2 sensor signal and start throwing CELs. I know URD makes a signal module that lets you use their test pipe... but I think it may be easier and cheaper to just put cats in and keep the ECU happy. It's simpler and it's what Toyota intended.

EDIT: I think the test-pipe and the signal faker thing would have been around the same price as the custom fab work and cats.

Ya I can understand that. So you said with your setup you had your headers with the air injection pipes, with an injection disable module. What was the reason or benefit of this? Do all the DT headers come air injection? I feel like I'm missing something since I didn't see that when I was researching them.

If thats something extra do you think that might be whats attributing to the car running like crap on 87 octane?

 

[Bumbo]

Without a tune most mods like this wont yield much of anything for power...

If you want it because you like it, then that is also a good enough reason too.

 

[Keros]

Ya I can understand that. So you said with your setup you had your headers with the air injection pipes, with an injection disable module. What was the reason or benefit of this? Do all the DT headers come air injection? I feel like I'm missing something since I didn't see that when I was researching them.

If thats something extra do you think that might be whats attributing to the car running like crap on 87 octane?

Bumbo points out, below, what I believe to be the primary cause of running like crap on 87. The ECU wants to keep the tune in specific parameters. However, the changes I made are hard for the ECU to deal with, so it pulls timing because more air is able to flow through the system providing the opportunity for lean condition. Retarding the cam and ignition timing is one way to avoid predetonation. However, running 91 makes the fuel harder to burn, so the knock sensors tell the ECU it's all good and let it run normally.

I put the air injection version of the DT headers so that I could change my mind about the air injection disable mod. Also, if anyone nosey pokes their head it, it looks complete and bolted up. The air injection system tubes dangling there with nothing connected would be a dead giveaway that something has been screwed around with. Unbenownst to me, the electronics aspect of the kit isn't exactly a stealth install but that's something that could be changed later.

Only the 2005-2009 DT headers have the air injection ports. I think the 2003-2004 headers do not. While I would suspect using the early version headers on an 05+ with the disabler kit would work, I couldn't find anyone who's done it. Keith at Dirty Deeds intended the installation to use the air injection version of the DT headers so I went with his program.

Without a tune most mods like this wont yield much of anything for power...

If you want it because you like it, then that is also a good enough reason too.

Absolutely, spot on, couldn't agree more. Bolt on mods are generally useless on the 2UZ without tuning support. The ECU fights us tooth and nail every step of the way.

 

[TrueBlue]

If you're looking for the power. The only decent power bank we can tap into is boost. URD supercharger kit offers 100horse and torque at low boost. Probably could push that to 150-200ish on high boost but you have to worry about internals. Starting next year I'm sourcing a 6.0 LS to swap into mine. I think I'll be the first and I'll document it all for anyone wanting to follow behind me


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