My Mac's cylinders were modified by TKG. They have higher compression and C-H ignition as well as bored out carb insulators and 1/2" carburettors. They do not have synchro-spark, the timing is fixed a 28 degrees. They have aluminum Abel mufflers which are no longer available. Everything on them came from C-H ignition.

One was originally a 28 but I changed it to a 32 cylinder and piston. The other was always a 32.

The mufflers are still held on by the original spring retention set up.