According to Novak's web site, the 3505 is 14mm. in fact, it says all 4 of the 550s are 14mm.

http://www.teamnovak.com/products/br...550/index.html

Of course, it also says "Allowed by ROAR" which ROAR has never publicly made such a statement. The rulebook still only allows "ROAR approved '05' size motors"...so even if they remove the '05' limitation, none of the 550s from any manufacturer are on ROAR's approval lists.

Guess you can't believe everything you read on the internet...