I would guess the only way to get 275cc from 2x150 barrels is to remove the plating, bore them, fit a new liner and replate that. It's not that uncommon infact to do on iron linered barrels.

Has DPS ever spoke to you Matt as I know they know who you are and I also know they have been buying Tyga 300 kits?
_________________
If I have to take the carbs off once more...