Toyota Tacoma Rear Lift: Icon RXT Leafpacks, Bilstein 5125, Timbren Bumpstops, U-Bolt Flip Kit 

I like them a lot - ride smooth and haven't sagged since install day. Out of the box netted me a 2-3/8" raise and I stored the add-a-leaf pieces for if I ever add weight or if they sag. You will need extended travel shock absorbers - OEMs won't work but the Bilstein 5100s should be ok but might want to verify their travel first.

Yes, you can leave the factory u-bolts and bumpstops on. I decided to do upgrades on those items while I was in there.

They’re made by Rubicon Express and are 2.5 degree shims. I did have to bore the center out a little more.

Great question. I did notice from 60-65 and Deceleration from 30-25. I installed a 2.5 degree axle shim on each side and helped drastically. I'd recommend a 2.5 or 3 degree axle shim between the axle and leaf pack to correct the driveline angle. Make sure the fatter part points towards the back.

I think you need a carrier bearing drop as the driveline angle is too steep without it.