...Which version should I choose, stainless steel or carbon fiber?
They both have their merits based on your needs.
...STAINTUNE stainless steel exhausts are by far the most popular choice because of the ease of maintenence. Stainless steel does not rust or corrode under the high-heat, high-corrosion demands of stop and go urban driving. They are packed with a spun stainless steel wool which never blows out and never needs servicing or repacking. Almost all stainless steel mufflers feature the removable sound restrictor. Stainless steel is best suited to bikes which tend to average extensive miles over the years. It's maintenence-free appeal lets you focus on riding rather then servicing a pipe. And consider this, if you sell your bike a few years later and want to sell the pipes seperately, you can simply polish the pipes back to a factory new finish. Since there is nothing that deteriorates inside or out, the pipes will hold their resale value extemely well.
...STAINTUNE carbon fiber exhausts typically cater to a slightly more exclusive club of rider. These mufflers feature a rolled lip edge where the carbon sleeve attaches to the stainless steel endcaps to increase the visual appeal. They differ from the stainless mufflers in that they are packed with a fiberglass sound absorption material and must be repacked over time. Because they use fiberglass packing, as opposed to steel wool on the stainless mufflers, they cannot be fitted with the removable sound restrictors due to heat retention. A carbon fiber muffler will typically save one pound of weight per muffler over stainless steel. Carbon fiber mufflers carry a craftsmanship warranty against defects in construction and fit only. There is no in use warranty for carbon fiber mufflers. Repacking is not covered under warranty.