3.15 LSD With Auto Trans (540i)

[abgrant]

Hey Guys,
Do you think I will see substantial improvements if I swap the diff for the 3.15LSD Diff while I still have the slushbox? I plan on an auto manual swap, but I want to get things that I can enjoy while it's still an auto.

My follow up question would be, if I can't get a 3.15, how crazy would a 3.64 be in the 540?

[Ernie D]

I swapped from a 3.15 to a 3.91LSD in my B40 swapped 530i and that woke the car up, almost to the point of it being a totally different car, plus mine is still a auto car also, its a very fun car to drive now

[abgrant]

I swapped from a 3.15 to a 3.91LSD in my B40 swapped 530i and that woke the car up, almost to the point of it being a totally different car, plus mine is still a auto car also, its a very fun car to drive now
Thanks Ernie, I appreciate it. How was your gas mileage after going from a 3.15 to 3.91? This may be a silly question, but did that cause excessive tire chirping/slippage when you stomped the gas or was it easy on the tires?

[Ernie D]

Gas mileage did drop a little, maybe at the most 2 mpg, I still get decent mileage with my car if I keep my foot out of it so to say, along with I have the dudmd chip in the DME also.
Engine runs about 900-1000 rpm more at 70 mph than when my car had the 3.15 in it.
If I stomp on it at a dead stop, its a 50/50 chance I'll start to roast the tires off the rear depending on type of road wether concrete or asphalt.
I swapped to a low gear ratio in mine to give me a better launch on the track