OEM SRT springs would give you roughly a 1-1.25" drop. That's the route I'm taking for my Altitude.
Road magnet makes two different types of lowering springs that a lot of people on here have installed with good results.
Just note, that if you have LL rear shocks they too will need to be replaced.
2015 Altitude - Billet Silver
SRT Springs, Taillight Bezels, Red Start Button, Pedals & Grille Mesh, Black Lugs,
Mopar 4" Chrome exhaust tips, 1.25" Bora Wheel Spacers, Sylvania Ultra H11's,
LED Taillight Bulbs, 15% Tint, Polk DB Center Channel, Mopar All Weather Mats