I changed my stock shocks to Boge Turbo Gas and I am very happy. The ride is better than before and the car in amazing on the highway.

There are a lot of variables you have to take into account when comparing shock absorbers, or more appropriately, dampers. The devices generally come in one of two flavors, standard configuration (dual?) and monotube type. These units have to operate under extreme variations in temperature. The monotube models are able to dissipate heat more efficiently and are therefore more desirable, and more expensive. The dampers control the action of the springs, ergo the ride and the handling. You want a good balance between ride comfort and handling (how well the car corners and the tires stay on the road).

The manufacturer chose a shock/damper that would satisfy the most people. The regular 940 uses Boge Automatics which are not gas charged. My understanding is that gas affects the characteristic of the oil. Things like foaming and heat dissipation. The general idea is that the gas shocks are firmer for this reason. Boge made the turbo gas, and essentially the same shock with different valving...the pro gas. The pro gas is stiffer with different valve action. IPD has a good comparison is their catalog when they describe the characteristics of the different dampers and their application.

You will notice a big difference regardless of what damper you buy. Yours are old and they don't wear out noticably, until they leak. Don't be surprised if the old ones 'seem fine' when you pull them out and compare with the new ones. You won't notice the difference until they get stressed and hot. The immediate difference will be how much better your tires stick to the road when it gets bumpy.