Ive only used the normal unleaded stuff from shell, i was running supermarket petrol (and still do on the rare occasions im not going to be in aberdeen for a bit but need petrol). I feel the car does work better with shell, but come summer ill be trying out the higher octane stuff
mine is very basic, no A/C, cd player, electric windows at the back, body kit, sunroof, ABS, spare wheel and back seats 
not sure bout the exact figure but mine should weight less than 960kg.
WAIT WHAT? no A/C? id die without my A/C and sunroof :O (yes im that lucky ive got both ^^ advantage of the SE...still dont have a cd player though..but tape to mp3 converters work great). Thinking about taking the spare tyre out since its going to be more hassle than its worth. I did take out the cup shaped ashtray (weighs about 5kg.. which i felt a bit un-nessicary) since im not a smoker
dont know the weight but not too bothered (alloys weigh in a fair bit more than the steel's were though so probably weighs more than it did stock)
