Still learning to tune my sails correctly. If a sail doesn't specify a range of luff lengths for adjustment, eg. 1 number, can I safely assume the one suggested in the spec's is maximum or +/- of that spec?

Trousers I think what he means is that if luff is specified as 430 does that mean 425 - 430 or does it mean 430 - 435?

Sorry nosinka....they are all different so no easy answer.

At any rate, even if they specify a range of length it is still often wrong and the numbers on extensions can be different. So rig it right, not to the numbers.

That means talking to the experts with the same sails, or see if there is a rigging guide video online for that sail done by one of the pro guys or designer.
Failing that watch the rigging guides online by lots of other manufacturers and yours will be in the middle somewhere. Obviously for your wave sail don't watch race sails videos