My friend has a '95 M3 with the track pipe and a remus catback and the track pipe it will eliminate the restrcition of the "Y" were the down pipe meets together and were the first o2 sensor is, it will go straigth down and then the 2 pipes will meet at the mid-pipe in a huge "H" resonator and there you'll have your first o2 sensor.
In other words it will be a real dual exhaust system but it may not pass emissions,
what you got now is
6cyl-flanges into 2downpipes into one singel pipe into 2mid-pipes into 2pipes on the catback
what yuo will get is
6cyl-flanges into 2downpipes into (H) resonator into 2mid-pipes into 2pipes on the catback
I hope it helps, I know is hard to get.