Yes you need a new motor. Yes you're friend does not know what they are doing. You can not just install a bigger turbo without many supporting modds AND A TUNE most importantly. The fuel pump is located in the trunk, so how would a bad pump make a sound in your engine like marbles?
Fill out your profile so we know your location. Then someone can tell you a GOOD subaru performance shop to take this thing to and get real expert advise, not speculative internet advice.