Ok so before I installed the stock it was Painful shooting the 870. Like pain for 3-4 days. After installing I took it out and shot 30rds from birdshot to slugs. It still has some recoil, but no pain afterward. I don't think its a 90% reduction but I think its worth the money if you have tender shoulders.
Pros: Lowers felt recoil
Cons: pricey
This review was written in the old system and had content requirements that are different than reviews written today.