Harko,
You're in NSW, aren't you?
According to the RTA "Guidelines for Light Vehicle Modifications"
The max engine size allowed (in cu. in.) is 0.294 x original weight in kg, where
- "Original weight" is the original (unmodified) "tare weight" of the sedan version of the vehicle model fitted with the largest engine available for the model but without optional accessories such as air conditioning and tow bar.
That means the max engine size = 1040 x 0.294 = 305.76, which presumably means 307/308 would scrape in. That 1040 figure is from memory - sedan kerb weight might be a bit more. I wouldn't have thought there was 100kg difference between a sedan and a wagon...
Anyway, the document can be downloaded from the RTA's website, at
http://www.rta.nsw.gov.au/registration/vsi06.pdfHope that helps,
RET