Quietening Down my 2.5" Difillipo Bi-Modal

[ihavesoldout]

I just had the following installed on my 6.0l V8 VF Calais V:
* HM headers
* 200 CPI Cats
* 2.5" Difillipo catback w/Bi-Modal (bi-modal flaps welded onto stock DPE mufflers)

I'm finding it to be great once I get to speed and cruise, i'm assuming the bi-modals close and at 60km or even 100km I can't hear the exhaust which is great.

My problem is from idle to the point you get up to cruising speed it is very loud. Sounds louder than the W310 at idle and even if I slowly accelerate from a stand still to 60km it is obviously loud and attracts a lot of attention.

I was thinking the whole point of the bi-modal was to quieten it unless i'm over 3k rpm but it seems the flaps are open from idle until about 2k rpm then close and back open around 3.5k rpm.

So my question - What can I do to quieten it down? It's also very low resonant sound at idle until 2k rpm, there is also a clicking noise coming from the rear right hand side, I think maybe the bi-modal is not actually working correctly or maybe even getting stuck?

Thanks

 

[lmoengnr]

What are you using to control the Bi-Modal valves?

 

[ihavesoldout]

It's a module that controls it based on vacuum pressure

 

[QAR]

Either the module is programmed incorrectly or vacuum is incorrect, or the muffler itself is not designed to be two-stage and the diaphragm valve just blocks off one exhaust vent. Wouldn't surprise me, most performance shops are doing that these days, total sham.
Take it back.