John Deere has added two new combines to its W-series range – the five-walker W550/W550i and six-walker W660/W660i. Main change is an increase in power output, with the 550 boasting a max of 290hp and the 660 a max of 350hp; basic harvesting spec remains the same as the other models' within the W range. The W550 and W660 machines will be available for the 2010 harvest.