^Thanks for the update.
Pressurizing that boost system was super helpful on my 996TT. On that thing, 80% of the hoses are hidden... Trip to home depot for test plugs and 3/8" pipe nipples. Listen first, THEN chase....
Also, any idea why this was only showing up now- well after you did these mods, and under the specific loads and speeds?
Finally- when people ask "what tune should I get?" I would often say "one that lives close'...or say "The tuner that your local shop has a relationship with".... unlike parts, a tune can be much trickier. And not that it is a tune issue (and clearly this wasnt at issue w Brad's tune), but just that a shop that doesnt know a tune is going to be more challenged with diagnostics or have suspicions about whats going on.....