I have managed after several tries and playing with mod pagespeed config to get it to work correctly with our classified script..Finally i have settled down to these settings under .htaccess:

<IfModule pagespeed_module>
ModPagespeed on
ModPagespeedDisableFilters recompress_images
ModPagespeedEnableFilters inline_css,inline_javascript

and in the pagespeed configuration file:

ModPagespeedRewriteLevel OptimizeForBandwidth

the last setting is critical to avoid changes to URL syntax and to HTML...
Keep in mind if you don't disable the filter for recompressing images you will have high i/o on cache location and if this location is on hdd instead of tmpfs then probably you will have problems with a classified website with many images....

Any thoughts and recommendations??