Right now, a Research Project converts 1/4 of your social production into research, and an Economic Stimulus converts 1/4 of that social production into wealth. The converted production is then eligible for research or wealth bonuses.
What this means is that if you run 100% social production, and have more than a +300% production bonus (let's say your bonus is +400%). Let's say you generate 20 base production (which means you generate 20 base research at 100% research). A Research Project would then generate 20 * ((1+400%) / 4) = 25 research, 25% more than you get by just running 100% research.
So how to you get to +300% production? Besides improvements, 9 maxed economic starbases will get you to +315% (a world can get bonuses from a maximum of 12 starbases), a well-leveled Singularity Power Planet will give over +100% manufacturing to all your worlds, and a Manufacturing Relic with 3 Archaeology upgrades will give about +33% to all your worlds. So, getting to +300% isn't too hard, and once you're there, you have no reason to run research or wealth ever again - those options will always be outperformed by projects.