Alum is much faster to weld and a lot cheaper material then stainless.
Plus you can make 10 times the number of parts from alum as it doesn't wear the dies.
You can make 1,000 plus parts with minimal wear when you stamp aluminum.
Be lucky to get 200 parts from the dies with stainless.
Then you have to way in the fact that the PFP was developed on factory pipes dime, Baxter paid no money out of pocket for the development of the pipe as it was made by FPP.
That sure helps lower the retail cost when you don't have hundreds of hours in development.
Also FPP owns the tooling for the manifolds. Edelbrok is just a foundry that cast them