Yes, you can increase width of image.
Please check my screenshot. I use FireFox with addon fireBug.
Then you can see file and line what you need to change.
FTP > templates > your template > css > style.css for you.
You need to change style for class 'gallery' and next class 'preview'.
Thanks.
Very much appreciated for the help
I have been playing with the code and still struggling a bit, the increase of image size does work however it shrinks the title and price Screen Shot 2014-07-17 at 1.06.55 am.jpg
is there any way to move the seller information and google map down so the information of title in the middle is not squashed?
something like this Screen Shot 2014-07-17 at 1.09.03 am.jpg