I can go to 3.5" if i wanted with my Kings OEM specs coilovers. Is not that they stop at 2.5" per se but shock manufacturers have recommended ranges that are within the specs of the vehicle recommended specs for proper operation, hence the OEM/Factory specification. In Icon case they advertise 2.5" of lift max because they give you a little shorter spring compared to the competition (13" free lenght), but You could ask them to add 14" long springs in their CO's when you order and then you could go higher if you wanted.
I don't know about the OEM Fox CO's, or Radflo, or Dirtlogic, out of the box King OEM come with 14" springs so you have a little more room to crank them up compared to Icons, Will see about FOX OEM's soon hopefully right
@novelmike ?
. Icons won't give you res or adjusters with thier CO's for the RAM 1500 application even if you ask, they say they have no room to place the reservoir. They're still great CO's and the cheapest performance 2.5 CO option on the market for the 1500's, maybe that's why they don't add the res to it as everybody else (King/Fox/Radflo and Dirtlogic) gives you a res and optional adjusters but they cost more money of course. (Dirtlogic doesnt have the optional adjusters). with Icon/Radflo/King you'll have to ask them to make you a custom lenght if you're going to pair them with a 6" lift kit. Fox and Dirtlogic have one version to fit 6" lifts out of the box.
And I think you meant to say Thuren instead of Icons when you referred to your likes for Carli and Icon ... , Icon won't sell you Fox or Kings, Icon sells Icon products