For point 1, I should add that there is no switch, the sound is the same all the time.
When starting from cold, it sounds slightly louder and with a tad more bass than when warm, but is pretty quiet. For normal driving it is pretty quiet, foot flat to the floor you get a strange sort of sound from the forced induction. It's hard to describe, but you are mostly looking out of the window concentrating on what is coming at you quite rapidly, and marvelling at how it can manage to have quite so much grip, whilst listening to radio 2 through your 12 speaker Bose stereo (which I think has always been standard).
To see the exhaust design, you can look at the Porsche website, www.porsche.co.uk, click on 911 then navigate the menus for the different models.
For point 2, the exterior has remained unchanged. The turbo light shape was adopted by the rest of the 996 range post face lift. The turbo 2 wheels have always been there, the only option is for the sport techno design wheels. These are the only 2 designs that come with 11 inch rims for the rear.
Power output has always been 420bhp 560Nm, X50 is an option to give 450bhp and 620Nm.
For colours, the newest one is Atlas grey, which is on of the most popular for new cars at the moment, but this was not available from launch, I think it has only been around for 12-18 months.
The interior has remained unchanged as well, so only certain options have changed (it has full leather as standard).
The metal sunroof is standard now, but I have seen cars without it, so it must have been an option to start with.
The comfort electric seats come as standard, but the sports seats (with the shoulder winglets, not the full on GT3 buckets) are a no cost option. The sports seats are the most popular I believe, but these have manual fore/aft up/down adjustment, with electric back adjustment. No memory function in the sports seats.
Parking sensors have always been an option.
The phone is an option.
Aero kit is an option, not many go for, and the chin spoiler is pretty vulnerable when it is painted. I have seen 2 designs of chin spoiler for the aero kit, so I know this changed at some point.
I know the sat nav, rain sensitive wipers and dimming rear mirrors are standard on mine, but I don't know if they have always been.
The standard exhaust tips are the single oval shape ones, which have not changed.
The chrome piece around the base of the gearlever, the Porsche logo on the handbrake and the squarer chunky gearlever are all options. As standard the centre looks a bit drab.
6-pot yellow callipers and ceramic discs have been an option for at least 2 years, and are only standard on the new turbo S.
Bi-Xenons with the washer are standard - I think this has always been the case.
The centre part of the steering wheel is leather covered as well as the rim (a minor detail) rather than plastic as on the other models. I presume this has always been the case.
The cd-auto changer is an option - not standard (which I think is cheeky).
If you get a lhd, you may not get the green top tint on the windscreen.
The suspension is 10mm lower than a C2/C4 as standard as well.
I don't know if with the LHD you can get a 90 litre tank, rather than the 64 litre tank in the RHD cars. I believe so, but I don't know if it is standard or an option.
I don't know of any other significant difference, aside from the speedo probably being in kph.
