there is no way that it is a genuine T4 if they are going for 2-300 quid...
a proper T4 is worth wayyy more now specially as you cant get the exhaust housing anymore.
the ones on ebay will be dodgy bus turbos or something?
my T4 which is a rs500 hybrid says ar.70 on comp wheel and ar.63 on exhaust.
can get the serial number if needed?