What is the tallest lift kit you can put on the IFS before needing to do a SFA?
the most lift you can put on the kj before having to do more than springs, shocks, and uca's is about 4" and here is how it will be accomplished:
front:
2-2.5" gained from springs/shocks
1/2" gained using a 1/4" top plate (or if you have the ability to DIY you can gain 3/4" by using a 3/8" top plate)
1/4" to 1.25" by doing a clevis lift
going over the 2" of lift mark will usually require the JBA UCA's...i have them and they are well worth the investment.
the most you lift you can achieve with these methods would be 4.25"-4.5" but you may run into issues:
in order to avoid damage to the stock CV joints you have to keep the distance from the center of the hub to the top lip of the fender flare below 23.75" IIRC (someone chime in if i am wrong on that number)...if you choose to go over that 23.75" number you will need to either ave a set of CV joints cut down (plenty of guys who can do it around here but it won't be cheap)...or you will have to buy the rcv ones through jba and IIRC they are around 1100 or 1200 for the pair...so my advice is to stay under 23.75" hub to flare unless you have relatively deep pockets.
for the rear:
2-2.5" springs/shocks
3/4 to 1.5" adding extra spring isolators
total lift max: 4"