I went from a VF22 to an 18G on my 02 WRX. Also did my runs at Bandimere (5280ft asl) on pump gas.
Mods with VF22:
-MRT 3" catless TBE
-pinks + GSS342
-TXS TMIC v1
-boost up to 17psi down to 15psi by redline - all it would hold to redline
-pump gas 93 octane
ran a 1.85 60' - 13.2@101
Mods with 18G:
-added GP MOTO 4-2-1 headers
-did NOT change tune one bit for headers
-20psi peak and to redline for boost
ran a 1.96 60' - firstname.lastname@example.org
Same spool as the VF22 but more topend.