Hiya Paul,
After reading this post and your question I thought I'd put this link on here for you.
http://www.turbosmart.com.au/boost_c...electronic.htm
Personally I don't like the use of manual boost controllers mainly due to the "wastegate creep". A manual controller will not allow the turbo to achieve your set boost level. An electronic one such as the one I listed above will help in the area you're requesting and eliminates "creep". It also has a feature to help with the operations of your WI. I hope this helps with your quest.
One more thing check out their product line they too have a dual stage controller.
http://www.turbosmart.com.au