Very impressed with the results so far. Only replaced the factory muffler, and left all the other piping stock. Sounds stock at idle, with a nice rumble under part throttle anda genuinely pleasing roar under full throttle. Low end torque is improved slightly and higher-RPM horsepower is definitely improved, according to the butt-dyno. Drove the same route I always do (over Pacheco Pass) and managed to get about the same mpg as always, even though I was driving 5-10mph faster than usual. So I guess it's safe to say mileage has improved...but not sure how much as of yet. Upon removal of the stock muffler, it actually looked like the inlet & outlet was closer to 2.5" with the 3" factory pipe being slid over the inlet & outlet pipes of the muffler.

I had been reading about all of the mileage improvements on this board with a simple exhaust upgrade and was quite skeptical as I figured the stock 3" exhaust should flow plenty for a 310hp v8. I have upgraded the exhaust on various vehicles, and except for my 12v Cummins Dodge (where the 4" turbo-back helped spool & EGT's), there was barely any improvement and even sometime a loss of low-end torque.

I'll be very satisfied if I see a 1 mpg increase...anything more than that would just be icing on the cake.

 

Congrats! I love my Magnaflows...you will too.

 

I have a magnaflow 14" muffler on mine. and its sounds pretty good. its not too loud though.

on my dak I had a 18" muffler and a high flow cat, and it was alot louder then my ram. so I think I'm gonna replace my cats with some highflows and that should make it alot louder.

 

It also gets louder when you remove the resonators...I removed the rear and it was a lot louder then whenI just had the muffler on.

 

I don't know if that's legal, in CA..

 

I dont think I have any resonators

 

The exhaust seems to have gotten a bit louder after the first few hundred miles...now it is a bit loud for my tastes. I am still running all stock piping, cats, and resonator, but is there anything I can add to quiet this thing down a bit? Would a resonated exhaust tip help?

 

I love my magnaflow!!! Yes over time they do get a little louder.