rodybmw

Some of you will remember that I removed my B&B exhaust after having it on my car for only about a month or so because of the resonant noise/vibration from 1000 to 2000 RPM. Well, it looks like B&B has finally realized that resonance and in cabin noise is not a good thing and they have come up with what they call "Purge Resonance Technology" (PRT) for Porsches. I don't think they have it for BMW 's yet. Here's the link and here's what they say:

"Purge Resonance Technology eliminates in-cabin noise.............Purge Resonance Technology is now available for all Porsche applications, including the Porsche Cayman S. This radically new B&B technology tunes the exhaust note - the result is pure German performance sound at idle and under acceleration, while the interior cabin remains a comfortable ride at cruise speeds. Once again B&B advanced technology has proven why it is the leader for superior performance and sound quality for exhaust applications."

jet190rs

sounds like marketing mumbo jumbo...

no technical info on how they cancelled out those annoying freqencies?

rodybmw

Not that I've seen......and at this point it only seems to be available for Porsches.

ferri

what type of muffler have you replaced to after removing B&B?

rodybmw

I put the original muffler back on the car...............for now.

vulcan747

Hi Rody
Saw your comments on the B&B exhaust just before sending a check to a fellow
that has a B&B exhaust for sale. I prefer a quite cabin but could handle a little resonance.
Was it that irritating and droning? Like you said the car is in the RPM range quiet a bit.
My sport sound threshold on a 1 to 10 scale would be a 3-4 and it looks like the resonance issue may make
this muffler buy a no-sale.
Did you also say performance and torque suffered?
Thanks
Tom

rodybmw

Hi Tom,

Yes, the acceleration did suffer with the B&B. At first I did not pay much attention to it because I was too excited about the sound, but after a couple of days I started to notice that the car wasn't accelerating from a stop as fast as it used to. The real revelation was when I switched back to the original muffler and immediately noticed that the acceleration and throttle response was much better and the car just felt more peppy. Also, the lack of the sound and vibration made the acceleration feel even faster and more effortless.

As far as the noise and vibrations levels inside the cabin goes, yes it was quite irritating and droning. I know there are a few people on this forum that have B&B's and it does not bother them at all. However, after trying really hard for a couple of months to learn to live with it I could not take it anymore. I really loved the deep sound of the exhaust when the car was first started and it did sound great from the outside, but just too much in cabin noise and vibration in that RPM range. I tried to drive the car in different gears to keep it out of that range, but that was not working out that well either. I know others on this forum had the same problem with their B&B's as I did. The fact that B&B is now making the PRT mufflers (for Porsche only) to address this specific problem shows that it is a real and significant issue.

Reading many of the posts here (as well as hearing some people's discussions in some of the SoCal meets) I realize that many people prefer exhausts with the loudest sound. However, I have come to realize that the tone is the most important aspect of the sound to me. I would prefer to have a deep sporty tone while keeping the sound volume level only slightly higher than the OEM exhaust.

As I said, there are some satisfied B&B owners on this forum, as well as some like me who have been annoyed by the resonance. So I really don't know which group you will fall into, but the only way to find out is to experience it for yourself. I had the chance to see and hear the B&B on a 545 (from outside and inside) before I bought mine. That was what convinced me to order the B&B. However, it's one thing to sit in a car and listen to the exhaust for 10 minutes and its another thing to live with it on a daily basis on extended drives.

dlevi67

AKA "we put the resonator back". That's exactly what a resonator box does! It eliminates sound waves at particular frequencies at the expense of some exhaust gas speed.