Disabling gk_nsp image resizing and gk_nsp_cache

I have a site built around the Gavick Storefront theme on Wordpress.

This uses GK News Pro on the front page and automatically resizes and caches files. I'd really rather it doesn't resize the files as they are then up to 150% larger filesize than the original files which are twice the size. So, to say the image resizing process is inefficient would be an understatement, and probably uses some fairly inefficient image resizing library on the server. And this adds an additional second or two to my load times, for a significantly poorer image result.

And I'd prefer to use the site's caching than gk's built in caching.

I'd love it is I could turn at least the image resizing in NSP off or disable it in the code, and also disable the caching if possible.
Any suggestions?

I should add that for this site I'm using PNG files - JPG resizing is generally not a problem. Either I need to change something on the server to achieve better results for PNG resizing in WP or WP itself is doing a horrible job with this. Either way I'd like to avoid resizing the files altogether and using the exact size files I've loaded.