The "if you have to ask" thing refers to the cost of acquisition (or to us mere mortals, the sales price) rather than any specific performance specification.
That's a bit different from Rolls indicating that "power is adequate" or Perreau [sic] (1) specifying power as "power - adequate".
Not sure if it was mentioned so far, but "nominal" means "not exactly" (similar to "virtually" which means "not really").
(1) Perreaux
