I upgraded to the 40 series flowmaster, single in - dual out, and the duals are dropped just before the rear axle. Front resonator was left on (06's with MDS have 2 resonators). Absolutely anincredible sound when starting up the motor and while reving it - very distinctive as I haven't heard that type of sound from any chebby's or frod's. It's on the louder side, but more of a strong - deeploud than obnoxiouspopping or crackelingloud. What is interesting is when the MDS kick's in. The best way to describe it is that is sounds similar to a helicopter's rotors (thump - thump - thump - thump). I must admit that I looked up in the air to see where the helicopter was but then realized what was happening. It will take some getting use to - Tow / Haul mode turns it off. My 4 year old son says it sounds like "thunder" and when I get on it, he says it sounds like it's "breathing". I will try to add some pic's of the install if anyone is interested. Overall, and despite my truck periodically transforming into a helicopter, I am very pleased.

 

How long does it take after resetting the PCM for the truck to realize any power gain after installing a new exhaust? It seems that my truck has lost a little after installing the flowmaster.

Uncle Hemi

 

i got the flowmaster 40's with resonators removed sounds real nice... never noticed any power gains really at all. maybe got an extra .1/2-1 mpg.. no tmuch they have been installed for about 3k miles now. i just love the sound. i didnt get it for performance though either.

 

You may not see any power increase. For example, your Hemi is engineered to run with a prescribed amount of back pressure. If most or all of that back pressure has diminshed sufficiently through the installation of a low-restriction exhaust system, you may actually experience a power loss.