Actually small size high stall converter almost always drops 60-120mph time. He might have specific EU problems...
We have somehow different tuning approach here in EU - almost no drag strips, testing/tuning car on autobahn at speeds you guys might not even consider.
Some guys on FB 6R80 boosted groups suggest stock AT cooler is enough while I literally cook every trans I tune on autobahn in n/a form...might be OK for those 10s.