Sniffles mane (from Sniffles & Snookums) 7 cm, (2.75"), first 5 plugs are 3.7cm (1.5")
Tail is 9.2cm (3.6") long
Her twin's mane was the same, tail was slightly longer.
Noodles mane 6.5cm, Doodles was 7cm. (suspect my Noodles has a slight trim, since the other three were all right around 7cm.) Tail was just over 9cm. Doodles tail 9.1cm.
I'd put 7cm manes and 9cm tails as average for the non-curly haired twins. =3