You won't need a 3.1 gallon tank for most of what you're going to be doing. In fact, you might be surprised by how far the stock 2.25 gallon tank will take you. It does, however, look like IMS adds most of the capacity on the underside of that tank, so it might not feel all that bulky. Looks like it bulges up a little higher in the front, though.
I wish IMS made a stock-capacity translucent tank, as it's difficult to see how much fuel you've put in the stock black tank until you overfill and make a mess.
If you really want to add some "wow" factor you might get a custom aluminum tank made. I'm not sure who to recommend, though.
Please PM me if you get a new fuel tank, as I'll probably be interested in your used stock one.