Drop brackets are just that. Drop complet rear suspension. But serve very little purpose beyond that. They give more ground clearance for deep snow. They change the look of the sled. As stated earlier they will also add ski pressure. If not done correctly, I have heard complaints of the suspension binding.
If I am correct in saying the pro action suspension has only 10.5” of travel where some other manufacturers had upwards of 13” of travel.
Also some of the pro action shocks were not rebuild able, I believe. You should check that first. I have had several shocks rebuilt over time at Pineer motor sports with good results. How you ride and where you ride will determine what you want and need in your suspension as well.
All this being said, I am no pro by any means. And I have only owned three sleds. Xt 600, 2002 viper, and current 2004 sx viper-s. There used to be a gentleman that worked at Pineer motor sports that was a wizard with yamaha sleds. Years ago he set up my 2002 viper. It was night and day when he was done.
All sleds need there shocks rebuilt over time, so you may want to do that no mater what. While they have them you may be able to have them revaleved. Add stiffer springs and give it a try.
Hope this helps??