Truck shaking around 60mph after mods installed

[cackler08]

About 1 moth ago I installed a Banks Intake and cat back exhaust. At that time I was running a Edge Evo and ruturned it back to stock, so I could send it into PHP (Which I finally did last week). I've noticed that the truck shakes when at speeds of 57-63 mph. I did not do this before the mods, while I was running just the evo or stock. it only shakes in that speed range. Could the mods (Air Intake) be causing this? If so will the tunes fix that?
The only way I can describe the shaking is whien your wheels/tires are improperly balanced, but that is usually shaking in the steering whell. This feels like the whole engine/truck is shaking. Any ideas?