I have enabled the filters below with Mod_pagespeed, but when tested via PageSpeed Insights it recommends to "Enable Compression" for css resources, to "Minify CSS" and to "Optimize CSS":
ModPagespeedEnableFilters rewrite_javascript
ModPagespeedEnableFilters rewrite_css
ModPagespeedEnableFilters combine_css
ModPagespeedEnableFilters combine_javascript
ModPagespeedEnableFilters combine_heads
ModPagespeedEnableFilters defer_javascript
ModPagespeedEnableFilters collapse_whitespace
ModPagespeedEnableFilters make_google_analytics_async
ModPagespeedEnableFilters canonicalize_javascript_libraries
ModPagespeedEnableFilters collapse_whitespace
ModPagespeedEnableFilters elide_attributes
ModPagespeedEnableFilters extend_cache
ModPagespeedEnableFilters flatten_css_imports
ModPagespeedEnableFilters lazyload_images
ModPagespeedEnableFilters remove_comments
ModPagespeedEnableFilters inline_import_to_link
ModPagespeedEnableFilters convert_jpeg_to_webp
ModPagespeedEnableFilters inline_google_font_css
ModPagespeedEnableFilters prioritize_critical_css
ModPagespeedEnableFilters rewrite_images
Subject site: http://goo.gl/vX8Dr4
At least for "Enable Compression" part, as far as I know the mod_pagespeed automatically activated mod_deflate for compression, doesn't it?
PS: PageSpeed Insights floats between 78 and 83 points without any changes to anything.