I am going to running a cam with .563 lift in a 2007 5.3. I see PAC has 2 different springs that should work. The 1218 has a max lift of .600 and the 1518 has a max of .650. Any benefit of running the larger spring? Or is it just overkill?

 

No need for 1518's over kill' the 1218 will do just fine '. I've run those on 581 lift and no problem '

 

I've heard its better NOT to over-spring the valve train.

 

I agree with this, why put extra stress on the valvetrain than necessary?

 

I'd go with the PAC 1218's!

 

^^^i agree