Goodness I built this thing when it first came out in 1974 and had it till a couple of months back when I sold it on Ebay for $60! It's a very good kit with some nice molded details. The Pfeil was a revolutionay aircraft that would have had IMO one extraordinary combat record if it had been developed earlier in the war. As I read on it during testing with the captured examples, it was faster than anything we had.
I believe the closest it got to combat was when one was being test flown and several Typhoons attempted to close in to attack but the Pfeil went full power and waved bye bye as the Typhoons could not keep up with its speed.
Like JJ says, make a dark wash and apply it on and let it dry. It will create shadows and add dimension to the molded details making them look even better.