"This chassis did not have chatter but we struggled to set up the chassis because we had to throw away all the data from the winter tests [with the previous chassis]. After the Brno GP, we modified the new chassis again and this one we used from Sepang onwards.
"For the engine, we concentrated on developing the best balance between power and fuel economy. We gained approximately five horsepower and 400rev/min more with the same fuel economy [compared with 2005]."
Of course, Rossi and Yamaha were ultimately denied the 2006 title when the Italian fell at the Valencia finale - handing Nicky Hayden and Honda the world championship - but Rossi and the new 800cc Yamaha will be seeking revenge next season.
Speaking in conclusion, Tsuji underlined the most important aspects learnt during the 990cc M1 era.
"The YZR-M1 was designed and developed to achieve the best handling. This concept feeds back to production bikes like the YZF-R1 and YZF-R6," said Tsuji.
"The adaptation of 'uneven-firing' technology to the in-line four cylinder engine has made a big improvement in rideability. This technology is spreading in MotoGP.
"Through 2002 - 2006 the engine management system has seen a lot of progress. Each year sees an increase in the number of items on the bike that are controlled by the EMS system."
Yamaha, like its main rivals, has already begun track testing of its new 800cc machine, which will be raced for the first time at the Qatar Grand Prix on March 10, 2007.