Well firstly I should perhaps point out I've never had a car with factory xenon lights - I'd always been sceptical about their extra performance versus their cost, and for the mileage I travel per annum on dark unlit roads I could never justify the outlay. What I did do for many years of BMWs and Mercedes was change the factory halogen bulbs (always H7 55W Philips or Osram units) for PIAA Extreme White versions. These always gave me a slight improvement in light output, with a much whiter light that was more effective at lighting the area ahead - I used two sets (typically $140 per set in 6 years so they lasted pretty well, and still have the second set in the garage)
Back to HID units then...
Well if I thought the PIAAs were an improvement I was in for a real shock with the HIDs. I can't quantify the increase but they were a HUGE improvement on the older 986 Boxster. Significantly more light output, especially immediately ahead of the front bumper and at the end of the headlight range. A lot of companies will claim increased beam range and all sorts of other boasts - what you have to remember is the beam pattern and the range are set by the headlight glass and reflector and the alignment of the headlight unit; you will NOT gain and extra 50 metres of vision. What you DO gain is additional light at the end of the headlight range which improves your vision at distance. Road signs almost fluoresce which is a bit strange at first.
When Porsche relaunched the Boxster in 987 guise, they included the projector beam type lens in the standard headlight unit. This brought an improvement over the old style 'reflector and glass pattern' of the 986 model, to the point where I felt it not necessary to re-install the HIDs. However havuign isntalled the HID kit the differences is greater with this headlight lens, quite unbelievable
Downsides ??
Headlight realignment ? - I haven't touched either car, just changed the bulb units and reinserted the headlight units
Blinding other drivers ? - the headlight beam alignment is the same so they are pointing away from oncoming drivers as they have to be by law. I have never had any other driver flash me, whether I've been following or approaching other cars
Lack of self levelling ? - the Boxster doesn't even have a manual headlight tilt switch on the dashboard !
- I guess the weight of the fuel tank in the front keeps the car pretty level. Heavy or bulky luggage has to be split between the front and rear trunks which helps to keep the car pretty level also
. The limited suspension travel and firm springing probably also help to reduce front end lift during acceleration
. My experience of observing factory xenon units in BMWs and Audis accelerating suggests that even self levelling units cannot fully cope with the change in vehicle angle. However, this may be an issue for Cayenne owners with the greater suspension travel and softer springs
. At least you have the tilt switch so if you know you have a heavy load in the rear you can compensate for it
Main beam - this still relies on the additional main beam halogen unit - mine is now a 65W H9 bulb, as opposed to the H7 55W of earlier cars. Either way the use of main beam is a strange thing
- all that lovely bluey white light from the HIDs is overlaid by an orange glow in the centre from the high beam; still effective but strange none the less. It makes you realise how different the HIDs really are compared to the standard bulb technology. I think litronics use the normal HID low beam bulb, but a motorised reflector alters the beam alignment.
I'll try to get some pictures of the 987 units late tonight, although I'm not sure how much success I'll have with the pictures given the very hot sunny weather we are having in Britain at present. Whatever happened to the usual cold damp British summer
.
Whilst doing my research I found the following websites quite useful...
http://www.xenonvalot.com/tuotteet_eng.html
http://www.hids4u.co.uk/default.asp - not the best website but their gallery has several cars with one halogen and one HID unit illuminated at the same time.
And another a bit closer home for you guys 'over the pond'
http://www.gohid.com/