If anyone hasn't tried SweetFX yet I came across this version called ReShade, aka SweetFX 2. Seems to be a lot easier to install and setup and has been running fine on on SH3-4-5.
Just a couple of before and after screenies to show the difference. I haven't even tweaked the settings fully yet this was just a quick install and test.
http://reshade.me/
Without Reshade
Reshade - Without.jpg
With Reshade
Reshade - With.jpg