here is my **pagespeed.conf**
ModPagespeed on
ModPagespeedFileCachePath "/var/cache/pagespeed/"
ModPagespeedLogDir "/var/log/pagespeed"
ModPagespeedFileCacheSizeKb 102400
ModPagespeedFileCacheCleanIntervalMs 3600000
ModPagespeedFileCacheInodeLimit 500000
ModPagespeedInPlaceResourceOptimization on
ModPagespeedFetchHttps enable
# Certificate Authorities directory, not your domain SSL keys
ModPagespeedSslCertDirectory /etc/pki/tls/certs
# Web Server's HTTPS client SSL key, not your domain SSL keys
ModPagespeedSslCertFile /etc/pki/tls/cert.pem
**for httpd.conf**
ModPagespeed On
ModPagespeedInheritVHostConfig on
ModPagespeedFileCachePath "/var/cache/mod_pagespeed/"
ModPagespeedRewriteLevel PassThrough
ModPagespeedEnableFilters combine_heads
ModPagespeedEnableFilters flatten_css_imports
# Direct Apache to send all HTML output to the mod_pagespeed
# output handler.
AddOutputFilterByType MOD_PAGESPEED_OUTPUT_FILTER text/html
#ModPagespeedEnableFilters convert_jpeg_to_webp
ModPagespeedEnableFilters collapse_whitespace,remove_comments
ModPagespeedEnableFilters extend_cache
ModPagespeedMaxCacheableContentLength 66777216
ModPagespeedModifyCachingHeaders off
ModPagespeedForceCaching on
ModPagespeedRewriteLevel OptimizeForBandwidth
ModPagespeedEnableFilters rewrite_style_attributes_with_url
#ModPagespeedEnableFilters rewrite_style_attribute (had to comment it cos it was breaking the site)
ModPagespeedEnableFilters fallback_rewrite_css_urls
ModPagespeedEnableFilters insert_ga
ModPagespeedAnalyticsID UA-4XXXXXXX-1
ModPagespeedUseAnalyticsJs false
Header set Cache-Control "max-age=2592000, public"
<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=86400, public"
</FilesMatch>