Originally Posted by mkoesel
Thanks for the info. However, I am sure with the proper modifications an N55 could make 408hp. After all, the N20 with single twin scroll can make almost 300hp, or 150hp/L.
As far as I know the N20 in its strongest 28i iteration makes 245hp, not 300.
And the N55 would not be reliable with anything above 350/360, certainly not to the extent Alpina would like it to be. There's a very good reason BMW and Alpina continue to use the N54 for the higher hp applications.