Banging and other bad noises, fun times.

[Fluffmarten]

Recently had my cat and parts of my exhaust replaced to try and get rid of a really annoying sounding vibration, worked for a few days. it rained and now the exhaust sounds terrible when it's a damp day and when i go through a puddle i get a sequence of short banging noises similar in sound as when my driveshaft failed me. don't think it's the wheel bearing as i only get the noise and vibration between 1800-2200 rpm

anyone else had this experience? the noise is really getting to me, and i've already forked out £900 on repairs this last year and i need to know it's nothing serious as i'm venturing out of the county next weekend
anything helpful would be much appreciated