Most of the parts you will need to do a DIY major service can be purchased at Ricambi America (https://www.ricambiamerica.com/) or on Amazon. Links are below.

Maserati Granturismo Major Service Kit – GTSK1 – https://bit.ly/2GoakP5

Oil Filter Wrench – https://bit.ly/2t8XvAC

Belt Stretch tool – https://amzn.to/2GpOGdh

Coolant – https://amzn.to/2GdLwdi

Motul 600 Brake Fluid – https://amzn.to/2TAanLy

36MM Socket – https://amzn.to/2GnQ0O2

Breaker Bar – https://amzn.to/2HS1Dik

Motive Pressure Bleeder – https://amzn.to/2Tx8aR9

Brake Fluid Vacuum Pump – https://amzn.to/2WDMx3z

Scan Tool – https://amzn.to/2UNC1oL

5w-40 Synthetic Oil – https://amzn.to/2GqBGEm