Guys i need some advice i am about to get a PD160 for my fabia VRS which has already been mapped my question is, will this cause any issues and will i have to go back to the mappers and get everything checked.

nah mate it'll run fine. I've got one on my car, had it from just after a bought it and its never gave any problems!

It shouldn't make things worse, but if you've had a custom remap, you may have lost out on a ickle bit of extra power by getting the car done before not after. The main benefit really is less smoke out the back IME...

Should be fine bud, It will tends to map itself as time goes on. ECU gets used to it.