Just noticed this thread so apologies for being so late (hopefully you've got it fixed).
I've been posting on the Facebook group regarding the HID kit.
I ordered 2 kits, one form Lush Lighting & one from HIDs Direct.
Both of these kits sent the same ballast which seems to be the "newest" revision. However on my 64 GTC it didn't work. Both kits, even when using the extra error decoders still gave errors. I think this new ballast doesn't play well with the already temperamental Astra canbus.
I spoke to a member on the Facebook group who has a 64 plate GTC & ordered from HIDs direct. When he ordered it (many months ago) he was given a different ballast. When I contacted they said the one I received was the latest & greatest so should work. If it was giving errors it's my car being temperamental & they didn't have other ballasts.
After some Googling I found out the older ballast which one of the members had was an EKLIGHT Q4 ballast. I actually found this ballast for sale on HIDs Direct & when I queried they said that this ballast would be compatible with the bulbs etc. It left me a bit annoyed as I asked if there was alternatives in my initial email & was told no, then when I asked about the other kit then was told yes.
It was becoming too much of a hassle for me though as I'd need to order the "older" ballast to test, pay for returns etc etc. & this was my 2nd kit with the same ballast so I just sent the kit back.
In a "last attempt" I ended up going with the kit from London Colour:
http://www.ebay.co.uk/itm/SUPER-CANBUS-E...gFwRd6DjGw
While a bit more expensive, I ordered it as I knew it definitely was a different ballast from the last 2 kits.
I fitted this kit at the weekend & this kit worked perfect. No errors on the dash & I've been using it over the last few days with no problems at all.
HIDs Direct & Lush Lighting were really responsive & helpful for the most part with everything so don't let the "dodgy" ballast put you off. It was just a shame I had to do some digging & be a bit out of pocket before I got all the info I needed.
I'd suggest though if ordering HIDs from HIDs Direct in future & you have a GTC Astra, try get the older Q4 ballast in your kit instead of this newer one as it at least is confirmed working by a member of the group.
Of course this is just my mileage on the HID upgrade path, yours might vary but thought I'd chuck in my experience
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If you need pics etc. for mounting or to compare ballasts give me a shout & I'll post them up for reference.