1999 and 2000 models breaking when the bike may have been overloaded with a passenger and luggage, and/or stressed by an aftermarket exhaust modification, so 2001 and later Hayabusas had a steel instead of aluminum rear subframe, adding to the 1999 and 2000 models' approximately wet weight. Performance and measurements Second generation (2008–2020) Suzuki lightly revised the GSX1300R for the 2008 model year, with a minor restyling of the bodywork, and fine-tuning of the engine's head, pistons and exhaust. Though the engine changes were relatively limited, they still yielded a large horsepower increase, and brought the bike into compliance with new noise and emissions requirements. Planning In 2004, market researchers from the US and Japan began working to identify which elements of the Hayabusa design had attracted so many buyers, discovering that, in spite of having its looks sometimes disparaged in print, customers were much enamored with the old Hayabusa. A redesign meant to strengthen the bike's appearance without departing much from the original found approval with dealers and focus groups. Underneath the skin, Suzuki decided to save considerable development cost by keeping major portions of the frame and engine unchanged. This was because engineers had determined greater power was possible without a significant redesign of the old engine, even faced with the need to comply with more stringent noise and air pollution rules. The target was to produce more than at the crankshaft, and they delivered , an 11 or 12 percent increase over the previous output. When the new Hayabusa was released, independent tests bore this out, with @ 10,100 rpm measured at the rear wheel. Suzuki's Koji Yoshiura designed the look of the new Hayabusa. He had previously styled the first generation Hayabusa, as well as the Suzuki Bandit 400, RF600R, TL1000S and the SV650. For research, Yoshiura traveled around the United States to bike nights and clubs for a first-hand look at the styling aesthetic of the Hayabusa custom scene and was inspired as much by the look and build of the Hayabusa rider as their custom bikes. While the second generation is very close to the first in overall shape and is largely dictated by wind tunnel tests, the raised lines and curves are meant to suggest a muscular build. Said Yoshiura, "I wanted to create a masculine form that complements a rider's muscular structure with hints of developed bicep, forearm, and calves." Technical revisions