Lift: Is clearance between the ground & an object. A suspension lift will move the frame & body away from the ground. A body lift will move the body away from the frame & ground (but the frame will not move away from the ground, so you have no additional ground clearance, only more room for tires).
Flex: Flex is created by longer springs
AND shocks (or struts). The longer springs compress / decompress more, and matching long-travel shocks / struts will be needed, or they'll limit the travel of the longer spring to stock travel. Spring spacers will NOT create additional flex. They're a spacer on top of the same-length spring (creating suspension lift), and have no way of making the spring compress / decompress any more than it already does. You will either need a longer shock / strut, or re-locate the mounting point to use your existing shock / strut (Jeff's kit uses both).
You basically have 5 choices with a kick:
Fender Trimming (aka "virtual lift"): Should be re-named fender "bending the lip in" really - the cuts are just reliefs to make the bending easier & to follow more precise lines. The often overlooked way to put on larger tires, keep the center of gravity low, will look good if done well, and costs only a few $$$ for hand-tools that you probably already have. If people were honest, they'd tell you they skip this option in the name of vanity - after all - lifts just look cool.
Spring Spacers $200+: The lift won't give additional articulation, but for $200 - who cares? It costs 1/4 the price of the OME (see below), making it the best bang-for-the buck way lift a kick. Jeff's kit has gotten rave reviews on quality & customer service.
OME 1.5" Lift $700 + S&H: Made by ARB - this is the luxury lift with the luxury price tag. The ride quality will drastically improve, and is the ONLY kit that gives 3" of additional suspension travel front & rear (OME is the only long-travel strut option). If you can afford it, get it - it's worth every penny.
Trail Slayer Solid Axle Swap (SAS) $4,000 + cost of axles & tooling: This puts Toyota solid axles in the front & rear of the Kick. Good for 33-35" tires. The only currently available SAS kit is made by Trail Tough, and gets good reviews. Like all Trail Tough products, it's well thought out, engineered & manufactured.
Home Brew: Most home-brew setups include some combination of the above kits. If you don't already know how to do it, then don't bother - you probably don't have the tooling needed, which will drive the cost of DIY higher than just buying the kit.
There are other kits out there (Calmini), but for the asking price, I've not included them 'cause they're just not worth it. Body lifts are the
- they raise the center of gravity without giving any additional ground clearance. This is BAD BAD BAD on short wheelbase vehicles, and should be avoided. The kits listed above are really the only options that make sense. From there - we're just limited by gearing, but that's a whole other thread.