I'm pretty sure the the Crucial DP I have is less expensive. Also it's divorced wastegate, high quality stainless steel, high quality ceramic coated, lifetime warrantied. My tuner was very impressed with my turbo response. I also have their uppipe which is really nice as well. It's a shorty DP so you retain your 3rd cat. The 3rd cat is not that much of a restriciton to justify replacing it with a high flow cat IMO.
www.crucialracing.com
Also, I agree with getting a custom tune. The AP is really nice. Try to take advantage of the package deal where you get the car protuned including the AP for $700...I think it is. I'd get an UP too.