Fuel warning on IMS 3 gl

I had the dealer install the IMS 3 gallon when I bought the bike. Just wondering if and when the fuel warning light comes on and how much fuel is left vs. the stock tank? So far have not run the tank more than 1.5-2 gallons down and am paranoid about running it empty.

I've got the IMS and I think there's about 1 gallon left when the light comes on. There was a thread on how to change this but it involves modifying the fuel pump assembly inside the tank so I didn't want to mess with it.

Ok, thanks. I'll keep going till it comes on and then determine how fuel it takes at that point. I was afraid it might not come on at all.

That's the best plan, it should come on ~140 miles and have just under a gallon left. Mine has an easy 35 miles of fuel left. YMMV

I know this thread is old, but just a reference point for others that may be trying to estimate range/fuel. I'm running a 13/47 combo right now. Repeatedly hitting reserve at 120 miles. Filling up within a few miles of the reserve light comes on I put in 2.4 gallons, leaving 0.6 in the tank. I'm not sure how much of that is actually usable, but take it for what it's worth. That puts me right at 50MPG riding dual sport gravel, ATV trails, etc.

Is your speedo/odo stock or have you corrected the speedo with a SpeedoDRD (which affects the odo)?
Also, are you heavy on the throttle or mild with it?

For reference, I only get 90 km (56 mi) per tank before my light comes on with my stock tank on my modded WRX. Heavy throttle. SpeedoDRD corrected (odo is off). Usually about 5.3 L (1.4 gal) to fill up at that point.

Speedo is corrected, so odometer is off a bit I'm sure. That's riding pretty spirited. Definitely not the usual fire road cruising.