Just so you know, there's a whole section for that type of question:
Suspension/Wheels/Brakes/Tires - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
Anyway, yes, cutting stock springs is dangerous. It's much safer to save up for the lowering springs and FE5 (Cobalt SS/TC) struts and shocks. You need the FE5 struts and shocks if your Cobalt is a base model (LS, LT, XFE) because the base model struts and shocks will blow out pretty quickly with lowering springs.
If you have an SS, then you don't need
to upgrade the struts and shocks, but if it's a 2005-2007 SS, the FE5 stuff from the SS/TC would be a good upgrade.
I'd suggest Canuck Motorsport springs. They ride similar to stock, give a good drop, and are very inexpensive.
Canuck Motorsport Springs
- $180 shipped
http://www.amazon.com/gp/product/B001SGYDK8?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00 - $68 Amazon Warehouse Deal
http://www.amazon.com/gp/product/B003YMPL1Y?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00 - $85 Amazon Warehouse Deal
http://www.amazon.com/gp/product/B001SGYLO6?psc=1&redirect=true&ref_=oh_aui_detailpage_o06_s00 - $30 each Amazon Warehouse Deal