If you are happy with your SPS in its current configuration I'd consider leaving it alone. Since the stock is already synthetic, I doubt you will gain much in an actual accuracy or weight advantage. You could spend a fair amount of money for a stock you don't like. I spent over $800 on a carbon fiber stock and it just didn't feel comfortable, the palm swell was just too big. Sold it. I also expect that your SPS stock flexes and absorbs some the the recoil pulse where a carbon fiber or chassis stock won't.
In my misguided youth I thought the factory stock was ugly and I didn't want it. So I scrapped it for some morphydite camo stock that doesn't fit me and is even uglier now. So I don't have the factory stock any longer. Figured rather than spend a couple hundred bucks trying to get one of their cheap molded stocks, I would upgrade to a nicer one.