I have heard of others changing the recoil spring on their P345. Mine ejects brass about 15 feet away while my P97 is about 5 feet. I haven't been able to find the information anywhere. Any help would be appreciated.
The P-345 uses a unique spring system. The outer spring is fairly light so you don't have to be a gorrila to pull the slide back. The inner spring only comes into play in the last third of slide travel. This system prevents battering the polymer frame while providing the tension necessary to make the gun work with a variety of bullet weights and loads.
This is not a 1911 where you can adjust the recoil spring to any load. Ruger's design works quite well though it does toss the brass a bit far. If you want to keep the gun working right, leave the factory recoil springs just as they are.