Note, on the 3.7's the alternator is controlled via the BCU PCM which is quite a complex bit of electronics (read...expensive) I personally would not add an ammeter or voltmeter into any of these circuits as Roadsters have proven to be generally reliable on electrics and you wouldn't want to add complexity or fc-uk up the circuit boards within the BCU with spikes & backfeeds
Agreed the 3.7 Roadster has a modern engine with full monitoring already via CANBUS. Since the introduction of alternators over 50 years ago, ammeters have generally not been used with them due to their much higher output and an unnecessary extra link in the electrical chain. As with most vehicles fitted with such nowadays the alternator has external regulation performed by the powertrain controle module (PCM, but read ECU).
In essence if there was a fault with the alternator you would know about it. Note also although some modern cars require the ECU's alternator charge profile be reset after fitting a new battery, your Roadster doesn't.
