I am convinced my turbo is getting louder, it has always been loud since i bought the car.
Its a STI 4, Is it expensive to fix? should i just leave it or do something about it now?

Thanks

 

Over time they do get louder, but potentially you are worried about failure. Are you losing coolant or oil? Is there screeching at start up or turning the car off? Any nasty plumes of smoke? Excess oil in the intercooler? You could remove the turbo from the car for specialist inspection and balancing, but obviously your car is off the road. If you were seriously worried about it arguably it should be checked as if the turbo let go there could be debris that might make it through your intercooler if you are unlucky and cause major damage. Sorry to sound glum.

 

Check your oil feed pipe to your turbos not blocked or in the process of being blocked,these can block meaning your turbo bearings are running dry,hence the louder the whistle/whine.If it is this fit a new feed pipe and depending on condition you may be ok.