I think the packet size is 1424.
C:\Users\x_ban>ping ipv6.google.com -6 -l 1426
Pinging ipv6.l.google.com [2a00:1450:4009:816::200e] with 1426 bytes of data:
Request timed out.
Request timed out.
Request timed out.
Request timed out.
Ping statistics for 2a00:1450:4009:816::200e:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),
C:\Users\x_ban>ping ipv6.google.com -6 -l 1424
Pinging ipv6.l.google.com [2a00:1450:4009:816::200e] with 1424 bytes of data:
Reply from 2a00:1450:4009:816::200e: time=30ms
Reply from 2a00:1450:4009:816::200e: time=30ms
Reply from 2a00:1450:4009:816::200e: time=31ms
Reply from 2a00:1450:4009:816::200e: time=30ms
Ping statistics for 2a00:1450:4009:816::200e:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 30ms, Maximum = 31ms, Average = 30ms
So do I add 28 for optimal tunnel size which would be 1452, oh my that's what Weaver said lol