These Springs are not for your grocery getter.  You will need 60lb Valve springs and your truck should make at least 500 horsepower for these to work properly.  Modified fuel supply is also recommended. Some pumps (usually 160s and 180s) will idle erratically after the install of these springs.  If you already have a big pump with just 4k s in it, try these you WILL NOT be dissappointed!

NOTE: 160hp and 175hp pumps require shim kit (DDP part# DDP624).  Additional cost is $6.00.