I just had fake duels with a flowmaster put on my 09 V6 3.5 Charger.

It sounds great at normal speeds, not too loud but noticable. However, when flooring at higher speeds it I get a real high pitched whistling type of noise - very loud, weird and annoying! I will not do this if your simply race the engine in park.

I tool it back to the place that did the work today, we test drove it and they have never heard anything like it - and they have done the V6 Charger before. On Monday they are going to put it back on the rack and do whatever to figure it out.

Has anybody ever heard of such a thing?

 

It sounds like there might be a leak in a pipe joint. Did the shop weld, spot weld or clamp the pipe intersections?

 

Weld.

It looks like they removed the OEM mufffer, put a single out Flowmaster in. Then ran the tail pipe as normal to one side. For the other, they simply ran it into the other tail pipe with a cross over and welded.
Seems like an OK setup, I was just going for looks and sound, not performance.

 

That sounds like a good setup and installation. Hopefully they will find the issue on Monnday, good luck!