There are a number of good intercoms on the market and no doubt you will get a number of opinions, two of my aircraft have the Sigtronics intercom for. A Cessna 152 in the training role this works just fine.
One aircraft has a Garmin audio panel with an intercom built in this is one of the best intercoms in the business bit over the top for a Pitts.
My personal aircraft has a PS engineering intercom, this was fitted some time back before the Garmin audio panel was available, this despite being the best part of twenty years old is still the best in terms of audio quality. Given that for the Pitts you are looking for a light weight installation I would take a look at the PS engineering products intended for two seat open cockpit aircraft.
PS Engineering :intercoms
I have no connection wth PS engineering except as a very happy customer.