How much horsepower
I have them in my 360 that's making around 370HP. They came highly recomended as an upgrade to stock rods by the race engine shop that did the machining on my block. They use them a lot in 400-500 HP builds. Eagle rates them for up to 500HP in a small block application.
The only thing I can say as fact, is they were all dead nuts consistent on weight, balance and dimensions, come with ARP cap screws and make stock rods look like something some made with a chisel. Eagle is a first rate outfit so if you stay within the design limits of the rod they are a good choice. Plus they are bushed for floating pins.