S6 "sputtering" puzzle update

[Scott Phillips]

Dennis,
 
IIRC and IMO based on your last post you have a weak coil. As boost
increases it makes it harder and harder for the spark to make the jump,
and therefore you're getting the sputtering under high boost. You
replaced the plugs with what I'd guess are "better" than the ones that
were in the car, and now you're getting a little better performance, but
not quite there. 

If you have another coil (or maybe in that path..coil wire..rotor..cap)
swap them out (or replace) and I'd bet you'll have your problem solved

If the sputtering is happening under other or different
conditions..(cause I haven't followed the thread).. please disregard..

HTH..

Scott '90 V8Q x2