Slim Line Tank?

I was filling the bike up last week and was surprised at the small capacity, the tank looks near-enough four gallons but it’s not. Looking under the tank, there seems to be a lot of wasted space, at least on the T100.

One of the things I always liked about Meriden Triumphs was the slim-line, American-style tank. Anyone know of any supplier for a tank like that?

 

It’s a 2013 865cc model.

That answers another puzzle, there were various references to pump positions on the Tank Shop website which I didn’t understand.

 

That’s the kiddie, like riding a Sportster!