Sometimes, you can reuse the OEM ones and just relocate the mounts, but many people opt for a smaller diameter shock up front so they can turn a little more. It depends on the application, though. In some instances, the OEM shocks won't have enough travel to be useable. What's the set up and what vehicle? Are we talking front or rear shocks?
I mean both, rear and front shocks.
I have two vehicles, a truck and a car. I use the truck for work and the car is a 1999 Honda Civic, I use it mostly on weekend or out of work. The truck is a 2002 Mitsubishi L200 (I'm from Dominican Republic, I think that this truck is not imported to USA, so you might not be familiar with it...)
I was planning on doing both vehicles air suspension, but the most important is the car because I have it really low and also the suspension is hard as a rock. With air I know the ride will be easier, such as to handle the car to bumps and irregularities in the road and also will be easier for my body

.
Anyway, and finally (I know I speak too much, but I just need to know

), when replacing the shocks with smaller diameter ones, you mean I just finding a pair of shocks that are small, shocks from any other car, just smaller that the ones I have, or do I have to look for special shocks such as air shocks or adjustables? What about the vehicle weight? Does it matters?
Thanks again!