The syn value will depend on the brand you buy. Dried noodles are free - both rice noodles and egg noodles.
The Amoy straight to wok rice noodles are free but the Waitrose chilled rice noodles are 7 syns per pack.
Fresh egg noodles seem to be 1 syn per 100g. Fresh udon noodles seem to range from half a syn to 3.5 syns per pack, depending on the brand.
Sorry I can't be more specific. If you post the brand name and type of noodles on here I might be able to give you a more precise answer.