I own a XB coupe and just went through the same dramas...
brakes i installed slotted and drilled rotors ... (more money than brains... not really) big difference worth the money. and the center hole prob on my mags was fixed
Every bush changed to urithane
lovell superlow front springs
Fat Front and rear swaybars
Rear leaf springs reset and xtra leaf added.
... my god was it worth it
all up parts cost me 1000 bucks.(trade/mates rates)
rear leaf reset cost me 400 bucks
did all the front myself with my bro(mechanic)
i'm running 17x8 and 17x10 simmons 245's + 275's