Did you guys see this

[Matt]

You would actually have less performance than stock since those charts dont account for added weight from larger tires or additional wind resistance from the lift. To get closer to stock performance you find the equivalent gear to stock then +1 ratio... hence 4.56s are a more rounded gear for the majority of the market.

[Matt]

Epiphany .... thought it is worth noting that 3.7L owners with the NAG1 might be better suited with 4.10s; i forgot the trans gearing was steeper already for 3.7L owners. I'll put together a quick table to see how the final drive ratios work out.

Edit: heres a spreadsheet with final drive ratios
https://dl.dropbox.com/u/24438380/Gears.xlsx

You can definitely see why the jump in performance from 3.07 to 3.73 for the V6 guys is well worth it! That's like the 4.7/5.7L guys getting 4.56s BTW

Based on this information, I still think the next gear option for our platform needs to be 4.56s since the majority of owners who will do this mod aren't concerned with a 200 RPM difference on the highway, and 3.7L owners have a good option already with the 3.73s.

Then, coming out with 4.10s would be a good gear for 3.7L guys to go a bit more extreme with their gears and the 4.7/5.7L guys to be a bit more conservative with theirs.

Also, don't make the same mistake most people make by comparing the worst OEM gear option to the next step. Think about it this way... whats the best OEM gear option available in your platform? (in this case, 3.73). So now pretend you're not "handicapped" already and have 3.73s.... what gear ratio would you like to have?

I need to take back what I said here.

What I said only holds true when you're dealing with the same trans gearing. It completely escaped me last night that the 3.7L owners who have 3.07 (or 3.55 option) gears stock have completely different trans gearing.

3.07 in the W5A580 actually has (practically) the same final drive gearing as 3.73 in the 545RFE.

So, you guys with 3.07's are not "handicapped".

[07JeepXK]

Jay has 33x12.50R18 Toyo Open Country MT's on 18x9 XD SPY wheels = very heavy setup. The 3.73's we installed in his 05 WK 3.7 made a world of a difference. Like Matt said, there is no need really for 4.10s for guys running the 3.7 liter due to the nag1 trans. Especially when a 3.73 swap is so much easier since you can get a front diff for a 4.7 liter that ready to bolt in.

[NoMatter]

Matt I can appreciate what you said regarding "the majority of owners who will do this mod aren't concerned with a 200 RPM difference on the highway" I agree.
But... I do see an awful lot of threads on gas mileage (I Know we don't drive fuel efficient vehicles. Primarily why I got such a great deal 4 years ago) But to put it out there someone who has the 545RFE and sees 2000rpm @75mph with the effective higher gear ratio from their 32's is gonna crap themselves with the gas mileage at 2200-2500 rpm! I'm fortunate to live here in Colorado with plenty of wide open spaces between places so my fuel economy is a bit better than someone who is stop and go, speed up and slow down. But as they say Slow and Steady.
- Just trying to discuss..
What effect would an over geared axle drive ratio have on the (4 Low) Crawl Ratio. Would that be beneficial or negative to off road performance?

[Matt]

The highway gas mileage difference isnt going to be that drastic between the two gears. But like I mentioned, after the 4.56s are available then it might make sense to appease the more conservative crowd with 4.10s.... BUT food for thought, if you have the 4.7L or the 5.7L and are concerned about gas mileage, then you're not going to regear to 4.10s since the 3.73s are sufficient. So even in that regard I dont see a market for 4.10s in this platform.

The lower gears would definitely help crawl ratio.

[NoMatter]

I totally agree that he would immediately sell more 4.56's simply since the guys running the 4 inch and 33's+ are really lacking in the performance, for the most part tend to wheel their jeep often and are modifying more than the budget boost crowd. I don't foresee myself getting a 4 inch kit and adding 33's or 35's, mostly because of the lack of availability and I really want to start a Stroked/Procharged Hemi project for a future street car... but in the meantime lump me into that conservative category. I would like to have some towing performance back while pulling a camper over these long mountain passes and still be able to afford the kids. I wheel 1-2 times a month from June to October or whenever the forest roads are opened, short season cause of snow. I feel that for myself a few hundred RPM on the long haul would be equivalent to losing a portion of overdrive.