European low-cost powerhouse Ryanair has ordered another 25 Boeing 737 MAX 8s worth $US3 billion at list prices to bring its total firm order to 135. Ryanair launched the high capacity MAX 8 variant, dubbed the 737 MAX 200, in 2014  with 100 firm orders and added another 10 at the 2017 Paris Air Show. It has a further 75 MAX 200 options remaining. It refers to the aircraft as the “Gamechanger” because of its higher seating capacity and increased efficiency. SEE our ratings for Ryanair. It will take delivery of its first MAX 200  in the northern spring of 2019 as part of plans to grow passenger numbers to 200 million a year by 2024. "The Gamechanger has eight more seats than our current 189-seat Boeing 737-800NG and incorporates the latest technology engines and winglets which reduce fuel consumption and noise emissions, ensuring we remain Europe's greenest, cleanest airline and lowest cost airline,’’ said Ryanair chief financial officer Neil Sorahan in the latest announcement. The aircraft, powered by CFM International’s LEAP-1B engines and incorporating advanced winglets,  is significantly quieter than its predecessor and delivers up to  14 percent lower fuel consumption than today's Next-Generation 737s. The Dublin-based low-cost carrier is Boeing’s biggest customer for the 737-800 and has taken delivery of 500 aircraft. The latest order means it has ordered 650 737s from the US manufacturer since 1994. "Ryanair's follow-on order shows once again that the high capacity 737 MAX 8 is the perfect airplane for low-cost carriers,’’ said Boeing senior vice president commercial sales & marketing Ihssane Mounir. “The airplane gives our airline customers more seats to serve their core markets, maximizing revenue potential at the best cost per seat in the industry." WATCH Spectacular landings and take-offs in high winds. The Ryanair order comes as United Airlines took delivery of its first 737 MAX 9 on April 23. United expects to take delivery of two more 737 MAX 9 aircraft this month and will have 10 by the end of 2018. The aircraft will enter United's schedule from June 7 with service between the airline's hub at Houston's George Bush Intercontinental Airport and five cities – Anchorage, Alaska; Austin, Texas; Fort Lauderdale, FL; Orlando, FL. and San Diego. It will operate on additional routes from Houston and Los Angeles International Airport starting June 29.