I've had my exhaust for a couple of years now and ever since it was installed, I've noticed this slapping sound that becomes apparent when I accelerate quickly from a stand still or low speeds. The slapping doesn't happen throughout the rev range, roughly between 2200 - 3500rpm but only if I try and go through that range quickly.

If I gently accelerate through those revs, the slapping sound isnt there, but

Just wondering if this should be of any concern or its just how it is for my exhaust?
Its got 4490's / 2.5" hi-flow cat / redback muffler / resonator.

where is the sound Back or front, take it to a mechanic and put in on a hoist (wait for the exhaust to cool down and grab it, Give it a good shake, look for anywhere it could be hitting, also check it hasnt come off the rubbers that hold it in place, if thats not the problem then id get some extra support bars added to hold it still, prob only cost $50

did a wheel alignment on a vx ss a couple of months back and i saw that one of the rear mufflers was close to the tailshaft and showed large signs it had been fouling on the tailshaft while moving, i pointed it out to the owner and he said it was impossible because he fitted the exhuast himself.......
Basically one to the welded hangers was bent from outta the box for his off the shelf exhaust and it was pulling the drivers side pipe into the middle of the car. so just check you cant bend afew hangers to get it sitting sweet.