I think the serializiation feature of TSNS and HSWC should be added to piston to let you cuztomize the extension length on the fly.
All you would need is a filt connection to a piece of piston in order to control its extension length (it could change the temperature).
Seems like a nice idea.However you can already control the PSTN extention using CRAY spawned PSTN or using DRAY to copy a PSTN part.
Also particle's TYPE digitisation using DTEC can be usefull in some cases.