Interesting Watts...if you need 6K revs to get some torque, you should trade this lump.
The peak torque is much lower than 6K for the 3.8 L ...so you may have been given the new 4 cylinder turbo or supercharged version we keep hearing about!
But, you may have gotten the 3.4L by mistake, as that has the peak torque up higher. Yes that must be it...the 3.6L can't handle the large increase in mass for the new Cab , with magnesium panels...about 180 lbs I have heard. You could have ordered a full soft top, that has 2 tabs to cover just part of the seating area, like the Boxter R.
You should really go for the Jag Cab, as that is all torque., with the V-10 engine new this year.
Final thoughts...Your later memos indicate you are becoming more familiar with the Cab, so your miles covered must be still quite low. Could you explain how or why you are reaching 6K revs, when the rev limit required in the Driver's Manual [that means warranty, and your peak revs are recorded for all time in the ECU ready for download] is 4200 revs with modest throttle until 2000 miles? We have heard mildly different rev-increases are sometimes better for run-in...otherwise you can apparently go from 4200 revs max to 7800 rev max instead , now with full throttle, as soon as you reach 2000 miles, and that cannot be good for the engine. Strange...
Back to 6K revs...using hi revs so early could have lost you a cylinder or two, or valves, which would explain the 'lack of torque'. Torque is only demonstrated at lower revs in a new 911-991, closer to 5K, and that only with higher throttle once broken-in after 2000 miles. High torque demands kills brand new engines, fast.
You may be in trouble Mr Watts, seems like you should not have a sweet Porsche...move to a grunty and less [or is it more] reliable Jag or Aston. V-8s is what you need. hey...why not a Camaro or 'Stang...loads of torque, expecially above 6K revs, no that would be 3500revs, the new metric system is confusing.
Enough fun...although heard those cab roofs are pealing the fabric off the magnesium panels at 100 mph or so...and, at the high California temps magnesium can spontaneously go afire?
Take Care...enjoy