Mine had an air lock for weeks.
drb5 even fitted a new thermostat as we thought the old one was sticking but airlock came back!!
It eventully went away with the old thumb over the header tank pipe/squeeze the bigger coolant pipe trick.
Adding a muffler could be dodgy if he wishes to pass noise regulations at the ScoobyShootOut.
Two recently failed but managed to pass with bungs fitted but that could change.
It's along way to go to be told you're too loud!!
Spotted a wee shunt approaching Kingston Bridge late afternoon with a silver classic at the receiving end!!!
Hope you and the car are OK if you are on here.
Been offline all w/e and didn't get the chance to put my 'spot' up Del!!!!
Like my runner!! It ended up dumped next to Prima in Milngavie after a quick pint @ The Inn.
Sorry to hi-jack.
Colin I touch goats and I have tried to call you.
(I can gurantee that this car is MINT. The best example of a UK classic in Scotland IMHO)