I use the genuine 255lph pumps on.my bikes. I used to work for a European car manufacturer, and we bought them both direct from Walbro and via a major auto parts importer.

They work well enough, but the Bosch "044" pump flows both more at no head pressure, and far more at actual running pressures.

We were buying the Bosch pumps direct for 17USD in 2009 - when we last bought them.

My job was to act as a liaison between global parts suppliers and the warranty needs of the end user(new car buyer). I was so good at my job the company left the US market in 2009. The latter sentence is a joke, but the former beset me with a short-term crisis.

Shorter: the Bosch 044 should support 700 hp, and the Walbro 255 lph somewhat less. Both pumps are widely used and highly regarded. Use with confidence and watch for counterfeits.