Looking at maybe regearing to 4.10 vs 3.21 and seems like Nitro gears are priced a bit lower then Spicer. The only thing I could find on them is they tend to be a little noiser then spicer gears. Any real world opinions? 4.10 is as deep as I want to go as I run 33" tires and do a lot of 75-80mph and have a 3.6L w/auto.

 

I've been running 5.38's for the last two years with no issues. Bought them from River City Offroad.

 

Run nitros in 4.56 in my '12 JKU, no issues, and quiet. Most of that I'd say is attributed to the installation.

 

I'm running Nitro's 4.56s in my 2012 and they are great, no complaints. As stated above the install plays a huge factor