I did the .50 straight rate springs up front and its been a great improvement. Nothing else done yet, maybe later. Same with the rear, just a heavy 8.3 ProCycle spring that does not require an adapter. I run 3" static sag with my 280 pounds squashing things down.
Just the springs help big time when you are not a light weight. The stiff rear spring handles my weight and my camping gear very well on tour.