with a larger tank and Thunderstorm cylinder heads which gave an extra . X1 Lightning (1999–2002) The X1 Lightning was the successor to the S1 Lightning line. They all used the Thunderstorm heads, fuel injection (Dynamic Digital Fuel Injection) and incorporated larger fuel tanks as well as completely different body designs. The most recognizable frame piece was the brushed aluminum tail section that swept upward and back underneath the two-up seat. S3 Thunderbolt (1997–2002) and S3T Thunderbolt (1997–2002) The S3 Thunderbolt sport-touring model was produced from 1997 until 2003, along with a mechanically identical S3T "Touring" model that ran through model year 2000. The 1,203 cc air-cooled V-Twin engine was mounted as a stressed member in a tubular frame. The powerplant output in 1997 and jumped to in the following years due to revised cam profiles and the new Thunderstorm cylinder heads. While the bike's overall look was the same throughout the model run, there were significant changes made in 1999 that set it, and later models, apart from the 1997 and 1998 bikes. The early bikes used a rectangular section steel rear swingarm, WP Suspension front forks and rear shock, a Keihin 40 mm CV carburetor, and a Performance Machine six-piston front brake caliper. Beginning in 1999 a new cast aluminum rear swingarm was utilized along with Showa front suspension forks and rear shock. The front brake caliper, while still a six-piston unit, was now made by Nissin. The most technological change came in the new Dynamic Digital Fuel Injection (DDFI) system, replacing the old carburetor. The S3 had a half fairing that surrounded the headlight and gave decent wind protection for the rider's torso. The S3T model then added lower fairing extensions that gave better wind protection to the rider's legs. The S3T also had hard saddlebags that could be color-matched to the bike color and were available in either "wide" for maximum storage, or "narrow" for a lighter feel. In addition to the lower fairings and the saddlebags, the S3T also came with a taller handlebar for a more upright, relaxed riding position. Each of the parts that set the S3T apart were available as accessories for the standard S3 model. M2 Cyclone (1997–2002) The M2 Cyclone was produced from 1997 to 2003. It was in the middle of the Buell line up between the puristic S1 Lightning and the more comfortable but heavier S3 Thunderbolt. The