Wotcha and welcome - the GX is an older impreza but with the same NA engine configuration you have.
your model series
RX 2.0 Normally aspirated engine
WRX 2.5 turbo engine, stiffer springs and thicker ARB's
WRX STI 2.5 turbo engine, more power, bigger hubs, turbo, intercooler, different body (Wide) compared to RX / WRX