Tank Holds 4.05 gallons (OEM X2 holds 4.1 gallons. OEM 650sx holds 4.6 gallons) That’s Only a .05 of a gallon difference or a 1/2 can of coke for the X2 and 1/2 gallon difference in the 650sx. Will work with X2 wave brace and most aftermarket pipes. Provides for Internal fill. Front fill neck is capped and can easily be cut open with a hack saw for those still wanting an external fill hole (see pictures).