You guys that actually can feel the difference are lucky. Twice I have changed suspensions. I put Progressive Suspension rear shocks on my 750 Nighthawk ( as recommended by the suspension gurus on the Nighthawk forum) and then had a Traxxion AK20 kit installed on my FZ-1 along with a custom (can't remember the name right now) rear spring on the rear shock as recommended by the suspension gurus on the FZ-1 forum. In both cases I was assured the difference would be transforming. In neither case could I feel any difference from the stock forks/shocks, particular considering the amount of money spent.
Now when I had my front fork oil changed recently on my ST1300, I got it back and noticed the front suspension was stiff, very stiff. I went back and asked what weight oil they used. 20 wt. I returned it and they replaced it with 7.5 weight as called for in the FSM and immediately on the first ride, it felt so much better. THAT I could feel. Other than that I can tell very little difference between custom boingers and factory boingers. Maybe I'm lucky lol.