I've posted some threads discussing making changes to our 1200 ute. Reading through old discussions engineering certificates are regularly mentioned.

The questions is:

Is there a list of certified changes like wheel size, tire width, steering wheel size etc or do I have to get an engineering certificate for each change to the car which does not conform to the car's original specs??

Generally ALL of the mods will be included in the Engineers Certificate. And that Certificate Serial Number will be printed onto the registration label that you put on the window of your car. If it's not on the sticker..then the registration is not valid. This is the way the cops think. It means that it's not been blue slipped with the modifications.

Some Engineers charge on a "per modification" basis, others just give a quote and charge you that. expect $300-$500 for a CA conversion.

Cheers,
Chris

Just to add to that, In the past when I have taken cars to be engineered, the engineer has said that sometimes the Registration Authority ( which ever state )
will stuff up and wont put the serial number on your rego sticker. To overcome this the engineers usually provide you with 2 copies of the certificate, one is for the Registration Authority and the other is your copy, and when you take your papers to the Registration Authority, have them stamp your copy to prove you have had it all passed and supplied them with the revelant information.