Have been looking at doing something with rear shock, spotted hyper pro progressive Spring kits, a lot cheaper than a new rear shock, anybody went down this route ??
In general, this does not work as well as a person hopes.
The spring is a big deal, but its nothing compared to the internal damping.
A rider can easily get away with a slightly soft, or slightly firm spring. Most of us are, right now.
Most oem shocks are set up with soft springs, and damping thats way too firm. This lets the bike sort-of work for a weight range of 140-240 lbs. Not great, but not dangerous.
So, we switch to the perfect spring for our weight....great. Now we have internal damping that way too stiff, and are down another 100.00 that could have towards a good shock.
Ive only done this on five different bikes, and never been satisfied in doing so.....Thick headed, and hoping for a different result from the same action.
On the other hand, I sent my stock ninja 1000 shock to Traxxion Dynamics. It is a virtual twin of what your Suzuki has. It came back as very good/excellent.
For 350, they changed the spring and altered the damping rates. You could see if something like that is available, because it was awesome. I later upgraded to a full Penske shock. It was better, but not 700.00 better.