I put the skyjacker 2.5" springs on that I bought from summit racing and it did not quite level it out. I have heard of people using the 4" which more than levels it. Then they shim the rear, any of you out there? The ride is noticably better with the 2.5", good investment, but wish I had gone with the 4".

 

if you went with the 4" springs you would need to get a longer drive shaft and longer brake line, and possibly tie rod. When I got mine they accidently gave me the 4" instead of 2.5" and I didn't notice untill I went to put them on and I couldn't get the axle low enough, with the driveshaft still hooked up to get them into the spring mounts. So your looking at a lot more than just springs if you want 4" lift.

The ride is noticably better with these springs though. Mine rides a lot better than other trucks with stock springs.