Hello from Poland. I'm driving 95 Sigma Automatic with V6 DOHC.
I've got a problem that keeps haunting me...
Around three months ago I decided to change big parts of the exhaust system since old one was in pieces (the pipes were so rusty that they were breaking regularly and I was tired of patching them every few weeks).
Anyway I went for central silencer and rear muffler from BOSAL - they are pretty
reputable exhaust systems manufacturer in Europe (or so it seemed so for me).
They make dedicated mufflers and mid pipe to fit Sigmas/Diamantes/Magnas or you name it.
But my problem is that my car makes low muffled tone. It only occurs at certain RPM range - between 1800 - 2500. As far as I can tell it comes from the tail muffler so I guess the problem lies in the muffler itself.
When I still had the original muffler the tone was still present but it pretty quiet (but still
distinguishable).
And one more thing and this is quite suprising for me - it seems that the muffler has to warm up to make this noise. When you try to drive the car when it it cold the tone is very quiet (nearly undistinguishable ) and it gets louder as the exhaust gets hotter - it usually takes a few kilometers.
I drove my friends Sigma - he still has original muffler as far as I can tell and none of this is sympthoms were present.
I've even put new catalytic converter today but it did not improve the situation.
Unfortunately I can't swap the muffler with my friend because his were welded altogether with pipes and stuff when he patched his exhaust recently (not very brightest idea but this is the way some so called "mechanics" work things out :|).
That would be it, I can post some sound/video clips if it will help in diagnosing the problem.

this is whats hapened in my sisters subaru when the qear muffler was pIERCED. Getting louder as it warms up is normal due to the heat expanding the pipes. Give the muffler some time to bed in and if the problem persists,then youre stuck with it unles youre willing to pay more for a quieter muffler.

sounds like you have an exhaust leak, could be a leaking gasket or a dodgey weld. And gets worse or appears when warm as the surrounding metals expands due to heat.

The fact its an auto and these cars seem to make a aweful drone around that rev range, not much that can be done with it.

One more thing - I've tried another piece of these (though used) and it made the same buzzing sound ;(. Seems it is their design what is a shame :(. Any recommendations? I can try to get a muffler from overseas (US or even Australia) but it would be great to have a proven brand that is known to actually make car quiet than louder :(

The only way you're going to get that quieter is if you replace the muffler with an OEM spec one. The problem is you've replaced your muffler with an after market one which is most likely a higher flowing one.

The only way you're going to get that quieter is if you replace the muffler with an OEM spec one. The problem is you've replaced your muffler with an after market one which is most likely a higher flowing one.

Thanks for the information, but I want to find out if is is my problem only or is it the problem with all 2nd generation Magnas/Veradas having this 3.0 V6 ?
I thought this is much better place since these cars are much more popular in the Australia than where i'm living (i've seen around 10 to date since 2006)

A little update after a few months:
I was so tired of this sound that I got rid of this rear muffler (BOSAL) and put cheap aftermarket one (made in Poland :-). Strangely it IS QUIET. Maybe not whisper quiet as OE but it allows to drive for longer than 10 kms without having a headache. And IT was pretty cheap - roughly AUD 50 (vs AUD 160 for BOSAL) . I started to enjoy longer trips again :-)