I don't think 19's are too large and I like polished wheels on a black car. Here's a couple of pics of mine.
<---Centerline Vantage FORGED wheels (ONLY 15 lbs each!)
<---19"x7.5"...fits great...especailly w/ Roush Racing springs!
<---225/35/19 Yokohama Parada Spec 2's...NO RUBBING!
BTW...You don't have to "settle" for what's available in our bolt pattern...You can have any wheel you like custom drilled to our 4x108 pattern as long as the offset is correct (just talk to whomever you purchase the wheels from about the proper offset for the Cougar). Just make sure you install some lowering springs (if you haven't already) or either wheel/tire combo (17's or 19's) will look silly with the enormous wheel well gap...If you go with 17's, buy 225/45/17 tires, and for 19" wheels I recommend 225/35/19 tires.
~CIII