From what I have read, you are looking at around 3200 lumens produced by a 35w 4300k HID bulb. At 55w you are looking around 3800 lumens from a 4300k HID bulb.
Also, the lifespan of a 55w HID bulb is drastically less (1,000-1,500 hours) than a 35w HID bulb (3,500-5,000 hours) due to useage which erodes the bulbs electrodes over time. This causes the arc inside of the bulb to get longer which takes more voltage to maintain the arc. Once your ballast reaches its max voltage output, the 55w HID bulbs will fail.
From everything I have read, 35w HID bulb is the way to go. Not only do they last longer, but I have seen pics of inside of projectors where the heat from a 55w HID bulb has damaged the reflector bowl inside of the projector which makes it useless. Not to mention having to replace your 55w HIDs more frequently.