We have done many of these manifolds with great gains for all setups. Most stock turbo users get an extra ~8-12whp from the intake work, and big turbo guys can easily get 15-20whp. We charge only $190 + shipping for the portwork as well.
Exhaust manifolds (are you stock turbo, S3, or aftermarket?) can see great gains as well, typically better spool, lower EGT's, better backpressures, and more power are what you get, and portwork can range from $295-395 or so.
Headwork is another animal, and we can custom tailor it to your needs. We have several different port profiles, and when combined with the right valvetrain components, can easily provide tremendous gains in the midrange and/or upper rpm's depending on what is required. Typical pricing ranges from $750-1900.
PM me if you have any Q's!
-Bob