There is no such thing as an 'ideal' amount....

[lovestolift]

....to overfeed when attempting to gain mass.

I have seen a lot of posts lately asking if "such and such amount of clalories" will allow the poster to gain the mass he/she wants. Here are the results of a study done at the Mayo Clinic. The short version is this: When a group of people are overfed to the same degree (in this case 1000 k/cal above their respective maintenance levels) the weight gained varied from 0.5 lb to over 10 lbs in an 8 week study. Everyone's metabolism upregulates differently.

The take home lesson seems to be this: Pick an amount to eat and see what the result is after two weeks. Gained weight? Keep eating that amount until you no longer gain and increase the amount again. Didn't gain weight? Increase until you do. No one can tell you how much you will need. Only through trial and error will you be able to figure this out. The only way to know is to try eating it (this goes for weight loss as well). While things like the Cunningham Equation will get you in the ball park of your maintenance level, you need to tweak the numbers based on how your react.

Oh, and to complicate things further, the amount you used to gain before will probably be your new maintenance level once you've put on a significant amount of muscle. I know from experience. Last summer I ate around 4000 k/cal and gained 15 lbs of muscle. Now, after adding 13 more lbs of muscle, eating that amount seems like it's not enough (I feel weak and my lifts fail more). This is common sense, but a lot of people miss it.

[Bramasole]

I couldn't find the part where it talked about individual variance over the group...the report just said that that the BMR increase wasn't linear. Was there another link?

[lovestolift]

It's in this part, in the first post:
"However, our metabolic upregulation isn't universal. In fact, there is a huge variation. Some subjects upregulate very well while others do not. In fact, in one study, the fat gain variation over 8 weeks of 1000kcal surplus was from 0.5lbs of fat gained to 10lbs of fat gained. In other words, some individuals will overfeed and gain huge amounts of fat while others won't gain a pound."