KK,

http://www.atpturbo.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ATP-WGT-022&Category_Code=WGT1

This is Almost what you want...Although the Opening pressure (18PSI) is a
little Higher than Specs.(A Boost Controller might correct that) AND the
opening pressure MAY be slightly adjustable by Tweaking the Rod Length.
Ask ATP next time you call.

EDIT:
Corrected by both FI and GSXR (Thanks Guys!)
Opening Wastegate Pressure can Never be Adjusted Downwards!
(So, The 18 PSI model ain't the ticket)

Attached Thumbnails

 

__________________
'84 300SD sold
124.128