We get this this question a lot: "How will changing the original springs for a set of GoWesty springs change the way my Vanagon rides?"
The answer varies, of course, depending on which springs you purchase: zero-lift springs or lifting springs—and it also depends on how worn out your original springs are. The latter is impossible for GoWesty to answer, because we have no way of knowing just how clapped-out your original springs are. Thus, the comments below assume your original springs are working as they would have when new (or close to new).
We designed these springs to behave identically to the original springs with the exception of one key thing: the rate is progressive. There is simply no downside to a progressive spring, other than the complexity of designing and testing it (which we have done extensively!). They are simply better. A well-designed progressive spring will provide the best of both worlds: the same comfort on small bumps and moderate loading, and much better stability on larger bumps and higher loading. Basically, as the vehicle is loaded—either due to larger bumps or heavier load—the springs react with a stiffer rate. This only happens when needed, so you don't have to give up your comfortable ride. What you do give up is the spine-crushing sensation that the original springs transmit through your backside as they simply let the suspension travel run out and bottom out.
The additional benefits of a lifting spring are more suspension travel and greater ground clearance. The downside is a higher center of gravity—which reduces lateral stability—and taller vehicle stance, which makes it more difficult to fit an already-tall vehicle into a low garage.
The rule of thumb is this: If you don't need more wheel travel for off-road driving (or if you have height-related issues), you should probably select our zero-lift springs. Also, it is particulary unwise to install lifting springs into a vehicle without also upgrading to a 15" or 16" wheel/tire package and upgraded shock absorbers to counteract the reduced lateral stability.