Gt spec has : brembos, ray alloys, cruise control, bose sound system, heated leather seats, bluetooth (I think its gt only), but if you suck at parking like me, look out for some with parking sensors.
Could be other stuff that ive forgot
As for things to look out for: make sure windoe motors work properly and are aligned (if window is up and u spray water at corners, it shouldnt leak into car like mine did.)
Clutch is prone to go at 60k miles
Check any mods that have been done as cheap mods destroy the car, I.e. ripspeed air intake can stall the car if you slow too fast like mine did.
When test driving, listen to any knocks or bumps that dont sound normal (the car squeeks all the time with the amount of plastic in it so dont worry about that)
Clicky axel when slowly driving forward or back, quick fix but just so you know what the noise is.