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Hi all. Im new on here and have a power problem with my 03 tundra 4.7. I have a spectre drop in filter, single in dual out magnaflow exhaust and just recently upgraded tires to 285 from 265 with 3" pro comp lift. I lost just over 1mpg have poorer handling with oversized tires and am now struggling to tow my 3000lb bass boat up to 70mph on freeway. was pulling better last season with stock height and tires.
Is there a reasonable bolt on or chip to get that 10hp or so back? I saw on another post something about getting the timing advanced to improve shifting, that has me very interested as my truck shifts very soft from 1-2nd gear.
any input is welcome, thanks in advance!
 

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Unless you are willing to bump up the HP (headers, maybe a chip and best an SC) you may have answered your question. Before you changed to 285's, you were happy with the setup, right?
 

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I'm sure your going to get a mixed bag of answers. Unichip and headers will be the most popular but I'm still trying to sort out what the real gains are from either (or both) Some say lots of gain, others say non (especially low end towing power).

To be honest, the best solution for towing would be to change the gear ratios. Not sure of the cost but there is no doubt that will correct for the larger tires. I'm sure it's expensive but if you add the cost of headers ($600 + labor), a Unichip ($600) and unichip custom tune ($400) you are looking at at least $2000+ and I'm not 100% convinced that would solve your problem .



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Well, you identified your problems: lift, larger tires, and modified exhaust. The lift is going to reduce your on-road handling, and if towing is important, you need to go back to the 265s (or 245s). Your gearing is not optimal with those large 285s.
 

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I think you are going to see most of the same answers here. The exhaust and intake don't necessarily help HP (especially in our trucks because of how they come tuned from factory). Most people on the forum have noticed that this mod in particular reduces their low end torque. As far as handling, no engine tune in the world is going to affect that. By lifting your truck, you raise the center of gravity and introduce more body roll. Stiffening your springs may help, but the bottom line is that your C.G. is higher and therefore you lose handling performance. Your towing problem has a few options. In my opinion, regearing will be your best option (if you want to keep your lift and 285s). After that I would say headers. Many people have said that they feel some low end torque returning with headers (especially if you can find some long tubes). A supercharger will increase your power, but SCs affect HP more than Torque (just the definition of what a SC adds).

Anyway, my two cents...
 

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Having someone re-gear it will cost around $1600 installed. I did that in my old 4Runner and it was a great modification. As far as gas mileage, did you factor in the increase rolling surface of the larger diameter tire? I'm just guessing here, but you may not be losing that much mpg if you factor in the 5-10% increase or whatever the diameter increase actually was. I would do the gears if you can afford it.
 

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Hi all. Im new on here and have a power problem with my 03 tundra 4.7. I have a spectre drop in filter, single in dual out magnaflow exhaust and just recently upgraded tires to 285 from 265 with 3" pro comp lift. I lost just over 1mpg have poorer handling with oversized tires and am now struggling to tow my 3000lb bass boat up to 70mph on freeway. was pulling better last season with stock height and tires.
Is there a reasonable bolt on or chip to get that 10hp or so back? I saw on another post something about getting the timing advanced to improve shifting, that has me very interested as my truck shifts very soft from 1-2nd gear.
any input is welcome, thanks in advance!


My dad used to pull our 3,000 ranger bass boat. That truck always struggled even at stock ride height.

Remove that spectre filter- go back to stock Toyota air filter
Get 265 75 R16 tires instead 31.6in diameter. biggest tires you can run on stock ride height.
remove the lift- get it back to stock ride height.
Keep the magnaflow. What size diameter piping do you have on the aftermarket exhaust?

Headers would be nice Doug Throley
Re-gearing would help but its not cheap.
Chris
 

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I have 285s also, and my Unichip helped offset the loss of power. But I don't really feel it kick in until about 3000rpm. I also have a dual Borla exhaust and a K&N filter.

Don't get an intake. :nono: You will lose low-end torque which will definitely be counter-productive for towing. :camper:
 

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Duel exhaust is killing you, bigger tires are killing you and a lift on a towing truck doesn't help at all. All these mods effect towing the most. Put it all back to stock and enjoy towing with it, or leave all that stuff on and enjoy how it looks. I think those are your only real options. Throwing thousands at more mods to try and fix what you messed with just doesn't sound smart to me, but if you have it regearing will get you back some power. Good luck, it sounds like you need 2 tundra's, 1 stock for towing and work and another to look custom.
 

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welcome to the forum :first:

The answers you have received really cover it. There is not really a way to get the lost power back. the 285's weigh substantially more than the 265s do to start with. To give you an idea, my stock wheels/tires weighed in at about 58lbs each. My 285s and newer wheels (which are pretty light wheels) weigh in at 80lbs on the dot each. That's rotating mass that you can't do much about, it naturally will kill performance. This is the weight alone, not to mention the added diameter and gearing retardation that happens.

So having bigger tires is destined to change the characteristics of your ride dramatically. Hope is not lost, you can get headers, you can get a single exhaust, and you still have the factory airbox which is a good unit to begin with. Duals SEEM to lose a bit of torque in exchange for HP for these trucks. I run stock piping(slightly modified) with just an aftermarket muffler and JBA headers. My truck honestly FEELS a little faster sometimes than it did totally stock, but in hot weather it is noticeable that my tires do have a negative effect on performance. I have towed a 2500lbs(approx) car recently, and although I never towed that kind of load when my truck was stock, it towed just fine.

One sure way to make your truck faster is to play some heavy metal on the stereo. I suggest starting with AC/DC or equivalent.:nod:
 

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Re-gear if you are dead set on staying with that size tire. If re-gearing is not what you want to do, second choice would be headers. After that, Unichip. Plain and simple.
 

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Re-gear if you are dead set on staying with that size tire. If re-gearing is not what you want to do, second choice would be headers. After that, Unichip. Plain and simple.

^--- what he said. :tu:
 

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I have 285s, 2.5 inch lift in front, ARB bumper etc. I tow a 5Klb camper over mountain passes in WY (South Pass and around Yellowstone/JH area) and there are very few places I cannot maintain 65mph easily. Mileage is anywhere from 7-10 mpg. One thing I did not see mentioned is a Tru-Speed. This is one of those devices that corrects the speedometer to compensate for the larger tires. One day while my my wife was driving I flipped the switch and the truck downshifted immediately and when I flipped the switch back it resumed its normal gear selection. I assumed that it just sent a correct signal to the speedometer, but after that I am not so sure. I haven't repeated that so maybe it was a fluke. Hpoefully someone here has more insight or info. on this.

Scott
 

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Discussion Starter · #15 ·
Thank you all for the input. I have ordered headers. I want to keep the look I have now and dont mind the handling issue so much as struggle towing my nitro, I pull it a lot in the summer up here, lots of bass tourneys. I didnt try premium gas yet, any chance that will help a bit when I plan to tow? I hate to take the 285's back off since they have under 3k on them but if headers dont cure I may have to in summer time. what about power programmers? I didnt see any mention of them, then I could set it back to factory when not towing for fuel economy right?
as for the larger tires making less miles I did look up the formula and these are 3.5% larger, so I add the miles to figure tru milage, still lost just over 1.5 mpg, not a big surprise with the lift and tires.
I will get some pics loaded soon, its looking pretty good, just need the stainless bull bar and shes about done.
thanks again for all the tips!!
 

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what about power programmers? I didnt see any mention of them, then I could set it back to factory when not towing for fuel economy right?
That what a Unichip is. I believe it is the only option you have for the tundra as far as programmers? I'm still up in the air about it myself. Quite an investment. $600(ish) for the chip and then you need a $400 custom tune to get any real benefit out of it it seems. Would be a good addition to your headers but your talking another $1000.


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