The issue isn't what you want or don't want. Asking about a BOV for an MB Diesel suggests that you don't yet understand the engine. The ricer comments, IMO, are a good natured ribbing way of suggesting that you should have a better understanding of what you're dealing with before trying to oudo MB's engineers.

As you know from DSMs, a BOV relieves pressure between the compressor outlet and throttle body when the throttle closes suddenly (letting off to shift). In factory config 'wasted' boost is routed back to the cmporessor inlet. In modified config boost is vented to atmosphere for that 'pchew' sound. Your 300SD doesn't have a throttle body or throttle plate so there's not much of a boost spike when you let off the pedal. The BOV would only open if the wastegate stuck closed and the overboost protection system failed. Very unlikely events.

In general these engine need more fuel before they need more air. An IC usually comes later in the mod sequence from a noticeable improvement standpoint.

Sixto
93 300SD