We used to be restricted to 0.886 IMN when I flew it, later that was reduced to 0.866 IMN for alleged stress avoidance reasons.
On air tests I was cleared to take them up to 0.91 IMN ( if my memory is correct) subject to a Mne of 0.925 IMN. Went quite happily at such speeds!
I've certainly flown them across the pond at 0.88 IMN in the past - but it guzzled fuel and there wasn't much point as it saved a whole 4 minutes in every 88 compared with cruising at the more sedate 0.84 IMN we normally used.
Glad you liked the sight - and sound!
The jet which set of the most car alarms I can remember was the Yak 141 at the Farnborough Air Show. But it also melted the runway!