11-18mm 4.5/5.6 + Cokin

I picked up the Sony 11-18 4.5/5.6, waiting for the a77. But at 77mm it will be pushing my Cokin P to the max. I have an ultra wide P filter holder. I also picked up the a mount to e mount adaptor. Will I need to go up to a Z filter system or will my P kit take care of business?

I use a p system with the tokina 11-16 which is also 77mm
at 11mm the edge of the holder is visible
I read the last 2 slots of the filter holder can be cut off, and then it is ok
I have not done this, I only zoom to about 14mm and everything is fine