I read a thread a while back that someone dynoed the before and after delete plate install and gained 5 RWHP and 5 RWT.
It was on another forum I believe.
Fine for a centrifugal or turbo.I don't think you want to buy the delete plates if your going to go with a Whipple of KB positive displacement blower. I believe those blowers come with intakes that bolt straight to the heads (so you wouldn't use plates whether or not they have butterflies in them). Saleen may reuse the stock intake though so you would want the plates. Any blown guys, please correct me if I've got that wrong.