Yet another question from the rookie ?

The plane I am building has a dual servo setup and as such requires a "Y" cable to be added. My problem is the "Y" cable seems to be about 2 inches short per side, Futaba cables are listed at 9" . So the question is How long can a servo cable be and can i just add the extended wires my self or should I / Can I buy extended cables beyond 9"
Atoz