So i plan on purchasing a 2" budget boost with the add a leaf for the back, my question is, can i also add a 2" shackle lift for a net lift of 4" in the rear?

 

No, you would only gain about 1" of lift at the axle, by increasing the shackle length by 2".

Increasing the shackles by 4", would give you 2" of actual lift. That is not counting the spring lift at all though.

So a 2" spring lift & a 4" shackle lift would net an actual 4" lift.

 

Alright, thanks for the info