I have been told that my 2.5 ton home AC would probably benefit from having more return. I have an 1864 SqFt home with 11 rooms total and 3 of those rooms on has a 12 x 12 return, main return is a 16 x 16. three three rooms are a part of an addition that was put on prior to me purchasing the home. the 12 x 12 is fed with an insulated 8in flex to the main return, where the main return is not insulated at all. I am looking to increase the size of the return lead to the bedroom. but want to make sure if it needs to be insulated or not.