To be honest I dont know anything about budget boosts. However I did do some research on it. So a budget boost just extends the vehicle up by adding a spacer to the top of the spring. What the guy should have done was take the factory isolator out and put it back in before placing the spring back in. If I read about isolators correctly, it should center the spring in place. That and your loosing 1.5" which I'm sure is dipping towards the front, I'd say you would need to have it in. I'd just buy some used isolators. I'm sure someone on this forum has them.
**EDIT**
And looking at your picture. If that's your rig sitting flat, I personally think the bump stops in the center of your springs are really close together.