We have a page below that lays out the calculations:

http://www.howertonengineering.com/Jet_Calc.html

480cc x 6 inj. = 2880cc

2880 x .2 (for 50/50 assume 15-20%) = 576cc

Since you need two jets, 576cc / 2 = 288cc per jet. Assuming 20psi peak boost you would need two .5mm jets. Other variables might push you up or down a jet size.

Another general rule of thumb is 150cc per 100hp, which happens to be 570cc, nearly the same as the 576 we got earlier.

Again, many variables can change the numbers, hopefully this helps you out a bit.