E36 BMW exhaust question

Since there's so many knowledgeable BMW specialists on this forum, I thought I would post this rather specific question here. My wife's '97 328iC has the factory dual exhaust. While at the bus stop waiting for my kids to come home from school, I got under the hood and listened to the A/C compressor, which seems to make a lot of clicking type noises. Prolly on the way out. That's another story.

Anyway, on walking to the back of the car, for some reason I put my hand down near the dual outlets from the muffler. I was surprised to find exhaust exiting from only one. I know that there is a diverter valve in the system somewhere. The engine was hot and idling. Does the diverter open after a warm-up period? Or is it RPM/vacuum dependent? Should a fully-warmed engine be using both outlets at idle?

What is the normal sequence of operation for the exhaust diverter?

Ah, I see now. Little vacuum actuator at the muffler exit.

And I see there's something called the "golf tee" mod that circumvents it. I suppose as long as it's working right (and it appears to be, since it's open with the engine off) there's little to be gained by defeating it.

Yeah I think its more of a sounds better mod than a performance mod.

yes, only the m3 actually needed the dual pipes.. the rest got the system that only opened up at WOT

Actually, it opens around 2500 RPM...