TE/TC IMS 3.1 Gal on my 2014 TE300

Fit will be same for 14-16. went on simply, its a little wider, no too much noticeable. But one thing I do notice is the weight and how it effects the bike. My forks are plush and I think the extra gas puts them a little down in travel. They felt a little harsh on the debut race. I will put the big tank on only when needed it only takes a few minutes to put it on. I reinstalled the small stock tank, the bike feels better with it. Most of my rides an races don't require the added fuel, but for some of our mexico rides it will for sure be on. PS I did not install (I lost it) the front seat connector screw, with the big tank it really is not needed, the seat stays on perfectly with only those 2 under the tank seat pan extensions.

Thats only a tiny bit bigger than stock right? My 16' 300 holds just shy of 3 gallons

yea but it get er over the 50 mile hump...many of our organized local rides are right at the 50 mile loop range. I was going on reserve between 40-45 miles depending on my throttle hand and terrain, I have not run this thing down yet all the way, but we did a 42 mile race and I had about a gal left which seems about right.
But I did reinstall the oem tank for our low mile high skill level ride yesterday. There is another event coming soon in which I will reinstall the "big" tank. 1.5 hours over a 10 mile course that's a little faster than the last one...I think one full tank will do, and its a good test anyway. I will leave it on so I can hit res and get back to the pits if I do need fuel.
Its worth having the "big" tank for sure for me as I have had to scrounge fuel from my buddies (mostly Beta300rr) on more than one ride.

Well original claim on the 15 tanks is 2.9 but mine only held 2.7 (measured multiple times) so going to an ims gave me just under half a gallon more which is well worth it for me! Plus I got it from a fellow cafe member barely used at like half the price. I have no regrets at all. I do like the oem fit better of course but I'm used to the ims now