This will be a 36-week, single group, open label study assessing the effects of Tadalafil plus Ambrisentan combination therapy in patients with pulmonary arterial hypertension associated with the scleroderma spectrum of disease (PAH-SSD). Standard outcome measures such as six-minute walk distance (6MWD), New York heart Association (NYHA) classification, and hemodynamic measurements will be assessed, as well as novel functional measures of RV-PV function including the transthoracic echocardiogram parameter tricuspid annular plane systolic ejection (TAPSE), contrast-enhanced cardiac MRI and heart rate variability assessed by Holter monitoring. This design (excluding a placebo arm) was selected for ethical concerns and to provide optimal efficiency and active therapy to all study subjects. It also allows for comparisons between the two monotherapies and with combination therapy.