Can I install a 3" pulley an a ss/sc with just an intake. Do I need bigger injectors or a reprogram? I will need a smaller belt to right?

 

Yes you can. Your stock belt will hold a 3" pulley. If you don't already have the intake on there don't put it on. The MAF's on Cobalts are sensitive and could cause problems without a custom tune. Injectors and a tune are recommended, I only ran my car with a
3" pulley and stock injectors and tune until I could get someone down with HP tuners to tune my car. What you are trying is extremely doable, I just wouldn't run it long term.

 

i currently run 3" with stock everything and wow what an improvement.

 

yeh I have had the injen intake on for about 2 weeks and no sel yet.