I'm not sure what it would cost to "upgrade" to a set of PPV brakes, but I bet you could get into a used set of Camaro or CTS-V Brembos for not much more, and they definitely are an upgrade.
'09 PSM G8 GT w/ Premium & Sport packages.
Go: LS3, BTR 233/250 (Stg IV) cam, Manzo 2" Camaro LTs, Kooks 3" mids, GXP axle backs, VCM, 100mm LS7 MAF, 3.27's, Circle-D 3600 stall, built 6L80E. Tuned by Me.
Whoa!: CTS-V/ Camaro Brembos, full Zeta II front and rear suspension swap w/ BMR goodies and BC coil-overs.
Show: LED headlights and fogs, VG Sharkfin, GXP bumper & diffuser, 10% tint, de-badged, CTS-V wheels.