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JLT Carbon Fiber Big Air CAI added and new tune / advice


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My '08 only has about 3500 on the clock right now.

I bought it brand new and initially had a Stainless works custom exhaust added (stock headers, 2.5 OR-X with 2.5" S-tube muffler catback - very aggresive and free flowing). When I added the exhaust I bought an XCAL-3 and tune for just for this exhaust from Lund. The new tune really ripped over stock and I felt "seat of the pant's" increase although I lost a bit of boost most likely from the loss of back pressure on the free flowing exhaust. It seems that boost would only pull about 5psi but the car really ran well.

So I recently added the JLT Carbon Fiber Big Air (127mm) kit and got an updated tune from Lund.


The initial tune hung the RPMs really bad and I reported back to Lund. Got another update to the tune and loaded it. Now the car shows more boost when I go full throttle (back to around 8psi) but overall it seems that it doesn't run as good.


Car seems to stumble a bit in first and second gear and just doesn't seem to sit, squat and take off like the initial tune. I am told from Lund that there is nothing wrong with the tune and hundreds are running it.


I guess I'm at a loss and a little frustrated. Any suggestions on why it doesn't appear to be as responsive as the initial tune? I don't suspect my plugs as the mileage is low and I am told I don't have to run colder plugs (NGK TR6) until I run more boost, so being at stock 8psi boost range should be fine. Does anyone have a different tune (VMP or other) with similar mods that they could send me to try out?


Advice, opinions appreciated



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That is a pretty big CAI for the relatively few mods you currently have.

I also have an 08 and track testing indicates over 700 HP crank with a Ford Racing 113mm CAI.

When I installed my CAI though, I also installed a smaller upper pulley at the same time.

If you are open to more mods & HP, I would recommend going with a smaller upper pulley and larger idler.

VMP offers a 2.5" pulley that fits TVS or stock blowers, and also has a 90mm idler that enables you to keep using your existing blower belt.

You will also need a pulley puller, and there Ultimate Puller is one of the best I have used so far.

They offer a package with the puller, pulley and idler.

If you buy those parts from them, they can also supply a custom tune for you, to work with the new parts and your existing mods.

Those mods all together should put you in the 650 HP crank range.

Another nice item they carry is a stock length heavy duty green blower belt for $80.

That way you can keep your oem belt in the tire inflator compartment as a backup, good to have for road trips.

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I have heard of that myself, and from other good tuners as well.

If you want to stick with the Lund tune, then I would contact him just to make sure, and let him know exactly what you are adding for mods.

He should be able to let you know at what point the tune might have to be changed.

If you buy parts from another reputable seller like VMP, he can supply a tune to match what you have as well.

Either way, they can email you an updated tune that you load to your SCT tuner, and then you can upload it to your car.

I installed a small pulley on a buddys 08 earlier this year, and he wishes he had done it years ago.

Excellent power gain and driveability is just as good as the stock tune, needless to say he was very impressed with the increase.

If you go to the 2.5" upper, ask and see if they recommend going to 1 step colder plug.

I went with a 1 step colder Ford plug, but I also have a few other mods as well.

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