Since I have an early 5.7, it has the heads the internet says are junk. In reality, they aren't bad, there are just better options from other engines. The 6.1 has bigger valves and ports. And more importantly, they have a smaller combustion chamber, so my compression will increase from 9.5:1 to around 11:1. Many people use the Eagle 5.7 heads on the early 5.7 because they are a cheap and plentiful and flow nearly the same as the 6.1. The problem is those have a very small combustion chamber and compression goes up to around 13:1. Thick head gaskets are available to remedy this and I was considering using the eagles. However, the eagles require eagle rockers and valve covers, and custom pushrods. Since the 6.1 was released while the pre-eagle was still in production, I can use my existing rockers, valve covers, and even valve springs. I may be able to get away with using my current pushrods too. They are Manley pushrods, so I'll be happy if I don't have to buy another set. I will have to get another intake. I was originally thinking of using the 6.4 intake so I could take advantage of the SRV, but they are stupid expensive and I'm not even 100% sure it would fit without hitting the firewall. So my options are either the 6.1 aluminum intake, or an eagle intake with spacers. (The intake runners are raised on the eagle heads so it clears the front of the block). Right now my preference would be the aluminum 6.1. I just need to find one at a reasonable price. In the end, I think the should be worth about 30-40HP more. The cam I have should like the increased compression too.