Originally I did the exhaust flapper mod by simply disconnecting and blanking the vacuum hose to the flap actuator. That leaves the flap permanently open for (IMO) a better sound but of course you no longer have control from inside the car via the Sport button.
For some time I've been wanting to get round to rectifying that and finally today I did.
I'd looked up the wiring diagram some weeks ago and it has loafed on my desk while I've been busy with other things.
There's only two wires to the solenoid and which is tucked up above the LH exhaust outlet together with a spherical vacuum reservoir. Access to the solenoid itself is quite restricted but the wires go through into the boot where access is good.
N321 is the solenoid in question served by brown/purple and black/green wires.
Eventually I decided to fit the switch on the side of the centre console. This was my third choice of switch location choices 1 and 2 having proved a little too awkward.
The lower side trim of the console is easy to remove via one bolt under the arrowed cover and then pulling gently to disengage the clips.
A careful check dictated that the switch be fitted so that the rear of it ended up within the area marked with a red oval to give suitable clearance.
I used a simple sub-miniature slide switch, £2 from Maplins. To fit it I cut an oblong hole in the console trim and after soldering on a suitable length of cable - I used speaker cable which matched the size of the OEM cable to the valve - secured the switch in place with 2 off 2mm machine screws. At this stage I checked at the far end of the new cable that the switch worked OK. The exposed terminals were covered with self amalgamating tape.
After that the cable was slipped up under the rest of the console working past the inner side of the seat so that the cable exited from the rear of the console with the rear seat squab removed. There's an OEM loom here that if followed leads straight to the LH side of the boot where I made the final connections. I just poked the new cable in with the rest of them under every other bit of loom tape.
The wires to the solenoid run along the LH side of the boot and are easy to see once all the polystyrene stuff is removed. There's no need to remove any trim panels.
I cut the brown/purple wire which is in the smaller of the two bundles and then soldered to the new cable insulated them individually and bound it all with more self amalgamating tape.
Finally a quick test before putting everything back together and bingo, all working as expected.
That's separated out one function of the Sport button. Next I'm going to look at how I might take separate control of the Sport (kangaroo) throttle map which will leave the Sport button controlling only the MagRide.
next a sound track would be good 
