I am thinking of running 37x13.50x20's and was wondering if I would have to regear. I have the 5.4 with 3.73 gears. If I do, would a k&n, exhaust, e-fan, and an xcal3 with custom tunes do the trick? Another question is how long could I wait before installing the gears after installing the lift wheels and tires if the performance mods listed above won't work? Also will this improve my gas milage and what gear ratio should I choose for the 37's. Thanks for all the help
- Jesse

 

I'd do all of that stuff plus 4.88s and Mag-Hytec differential cover. Don't do the K&N. Get a S&B or AF1 3.0". I'd also consider getting the Xcal2, it's cheaper, does the same thing, and doesn't have problems. The Xcal3 isn't plagued with problems but they do have a few. E-Fans are a good mod but do not buy the kits from TP. The kits they sell have a LOT of problems, just ask Josiah. Josiah can point you in the right direction towards getting a nice set-up so just shoot him a PM. The performance mods are going to help but they are actually going to put more strain on the transmission. The gears are going to "lighten" the load that the transmission is going to be under. So at a minimum do the 4.88s and the Xcal2 so that way you can reprogram for the gears and tires. Keep in mind the Xcal2 doesn't go up to 4.88s but whoever does your custom tuning will be able to make the changes for them within the tune, very easily.

 

alright, sadly enought that isn't what i wanted to hear lol. I highly doubt I will be able to do all of that then the lift wheels and tires. I already have the exhaust and k&n. My dad works at a body shop and got me my fans for free. I was hoping a xcal custom tune would do the job. Would just gears work or is the xcal a must also. How much do the gears run. Im now begging to think of just running 20's and 35's. This sucks!

 

The Xcal2 would be a must with the gears since you'll need to calibrate for your gears and tires. Since you've got the K&N now, keep it. Don't waste your money on another one. What kind of E-Fan did you get?

 

I am not really sure. He took it off of a 2003 lighting. After installing the lift and tires, how long could I wait to regear?

 

You could wait, there are several people on the forum that didn't regear i.e. Josiah. I believe he has 3.73's. It is a good idea to get some mpgs back and take some off the stress of the engine and tranny.

 

ive got 4.88 yukons front and rear and they are doing great. I havent noticed any mpg increases though. Performance wise youll see a nice difference from the 3.73's to the 4.88's. Ive had mine for 6 months now and love them!

 

Well do you think if I got the xcal then waited about 6 months to regear it would be alright and not hurt anything?

 

I personally think 4.56 gears would be ideal for your setup. I have them with mine and it's plenty of gearing.. I pull a trailer with a few 4wheelers every weekend effortlessly too.

 

well I am looking for the best overall gear. I need the best gas milage possible, and I want to beable to pull a trailer if needed, and I alos do not want to lose all of my top end. So with that said...4.56's or 4.88's? lol

Also thought I should just say I will be getting is the 4.5" superlift. dont know if it matters or not

 

4.56s will give you a little better milage with slightly lower rpms. I'm getting 15mpg with 38s and a 10" lift. I just think 4.88s are badass but overkill for what you want.

 

So then if I just got my lift wheels and tires, started to save again, and then in about 6 months got my gears it would be fine? I am just really worried that I am going to get my whole setup done then have to do gears right away and not have the money, or not regear right away and screw something major up.

 

Regardless if you can 'live with' not having gears, it's going to be hard on your tranny pulling those big tires without regearing. I'd just do it all at once, I waited a little longer to do it correctly.

 

Edit. I didn't realize you had made a post earlier which mentioned it. I think 4.88s are perfect for anything 37"+. I loved them with my 37s.

 

15 mpg is pretty friggin impressive with 38s...