I am sure this has been discussed before. But I have spent 20 minutes in searching the archive without much luck in finding what I am looking for. Hope this is not too bad to ask again.

I accidentally shot a 220 roll of 160VC with the camera set to 320 ISO. So the entire roll was underexposed by 1 stop. I can push process this roll with my Jobo processor by extending the development time to 3 minutes 45 seconds. My questions is what I should expect the images to come out. Will I get weird color balance? Will the film grain be OK still?

The roll was shot during my day trip yesterday to the Pinnacles Monument National Park in California. It was a bright sunny day yesterday but the sun wasn't like summer days. It was really perfect for scenery shots. Unfortunately I found out that the ISO setting was at ISO 320 when I finished the roll. I know if I process it as usual the images will be grainy and poor colors as well.

I hope I can still get reasonable fine shots by pushing it one stop in processing. Your comments will be appreciated.