I've heard around $350 for the port job on the Eaton and power gains around 30-40hp. If you have the stock plenum and TB ported as well, 60hp plus can be achieved.
it cost me $500 2 years ago for just the blower and i picked up 50 rwhp and that was with a stage 3 port job..........now i hear theyre comin out with a stage 5