You can fit both ballasts on the passenger side inside the little plastic under light tray.
Drivers side, one bots nicely to the threaded hole the SMIC would use and the other sits nicely under the headlight itself. If you really want them hidden, take the bumper off and fasten them to the lower headlamp retaining bolts - the only
problem then is you get a failed ballast you've got to take the bumper off again to get at them
Other option is behind the bumper if you go in behind where each side grill is - i'll be going in there when i put HID in the fogs