Anyone up on turbo issues?

Hello,

Well as per the title I believe I have a turbo issue, or perhaps a boost leak.

Wouldn't mind someone else view on this to find my problem, its hard to descibe but sometimes when driving, if I boot it the turbo normally comes in around 1500rpm id say, some times its like a big lag and doesnt spool up unitl 2000+rpm and when it doesn't spool it kick a load black smoke out the back.

Weird part is, you can hear to what sounds like the turbo spooling but not the usual woosh sound but more of a high pitch squeel?

Any ideas would be appreiacted, its a Fabia VRS BLT, it has been remapped but its a descent enough map and i haven't had any issues in the past with it.

Thanks