General Maintenance & Repairs - rattling - exhaust or driveshaft?

I have an A4 SS. It has pacesetter longtubes, ory, cutout and stock catback. When ever I accelerate the car rattles in the back, only when I'm accelerating, never when I'm slowing down or if I just rev the car. Its coming from the rear of the car and depending on how fast I accelerate it will rattle more or less. Would this be my u-joints or just my exhaust rattling?

Moving to General Maintenance & Repairs...

im going with exhaust

Driveshaft will give you more of a vibration...... Im thinking exhaust

excellent. thanks! i'll get working on stopping it