After spending some time recently investigating availibility of a of-the-shelf exhaust header for GM's 2.8 or 3.4L, or more accurately lack of any such product, I decided to write good folks at Calmini and ask them about any such possibility.
As a response I got fairly positive feed back
here's what they wrote me:

CALMINI has always been asked to build a 2.8L header. Ironically
enough a prototype set (complete with the y-pipe), is already completed and
has been for some time. However, the goal of an elevated interest in this
header has not yet been seen. However, I am more than certain that with
enough orders, no less than 30, the 2.8L header would become a reality. If
you can generate the necessary 30 orders, the header can be placed into
production. Please have all interested parties send an email to
Davidk@calmini.com with the topic line of 2.8L GM header. A list will be compiled and we will work
from there. Interested to see the response. Thank you for your interest in
the CALMINI Isuzu line.

So what you guys think, do we have enough interest or not, lets pull our weight together and maybe this will finally happen.

Hope this posting will help to further the cause.

ElBarto.