Look at MarkD software, I've been meaning to get it for my car, but 400hp has been keeping me plenty entertained.
As for the exhaust, before you spend $$ on an aftermarket muffler, try the muffler delete mod with exhaust tips. You will be surprised at the result and so little money.
www.enthusiastauto.caNeed a car???
--'00 BMW ///M5 .:Jet BLK/BLK:.Individual- Modded
--'07 BMW M5/6.:Indianapolis Red
'91 BMW 850i J Spec Modded
'88 BMW 635CSi Lowered
'81 MB 500 SEC Koenig WILD RIDE