Here in Europe, there are quite a few BMW tuners we're familiar with; AC Schnitzer and Hartge being the obvious ones, with Alpina establishing a brand on motorsport and producing tweaked BMWs.
Over in the US however, there's a company doing great things with BMW that we hear very little of. Dinan has been fettling BMWs since 1979 and has established such a strong reputation in the States that its parts are available throughout North American BMW dealers. Moreover, complete Dinan vehicles are sold at a third of all USA BMW dealers. A fairly big deal then.
This vid from Motor Trend goes behind the scenes at Dinan, interviewing founder Steve Dinan, going round the workshop and exploring the cars. What becomes apparent is the attention to detail in everything Dinan does; testing is rigorous and the development period for parts quite long as they literally go back to the (3D) drawing board chasing improvement.
Mr Dinan seems like an amiable chap too, even if that impression is shamelessly augmented by MT's soppy backing music. Fortunately that attitude changes when Dinan's 450hp 1M Coupe becomes the focus. Stick around for that one. Oh, and the 670hp M5.