no significant mpg change with addition of an exhaust. you would have more chances of mpg change with intake and/or ecu remap where the change goes both ways

 

[the only real way to know is to try it. the efficiency and increase from a freer flow or the system may need the back pressure form the exhaust. it really depends on the design. this is especially true for 2 cycle motors.

 

i installed a xpipe in the front where the 2 resonators were... since than i can def. feel the increase of backpressure. So by adding free flow mufflers, i think it will balance out...

 

I noticed no change in mpg in my old 550i compared to it's Dinan-ized state. My first mod was the Dinan exhaust which was the only mod I had on the car for a good 4 months. I still got 17-18 city / 25-26 hwy. After those 4 months, I added more Dinan accessories: CAI, TB, ECU remap, suspension, and forged 19" rims. I did not add the 3.45 differential, and despite the increase in hp to 390, mpg remained the same.

 

then you said heck with spending $$ on a v8, lets go all out on the v10

 

Honestly, it's probably not going to make much of a difference; you won't gain HP or lose/gain MPG, certainly nothing you'll notice. It will sound better, though.

As I mentioned on this or another board, the best gain for this car would be from new headers and a good tune, probably a 30 HP gain and a ten percent increase in MPG. Unfortunately, I haven't found any aftermarket headers for the standard 6 series. It would be great if there was aftermarket tuning software for our cars, too.

 

Exactly! However, this upgrade lead to massive fuel leakage, resulting in uncontrollable smiles per gallon.

 

loool, do people around you complain about gas prices? Than ask you, v10! what!!!!!! are you kiddddding? lol