Turbo muffler delete just gets rid of a piece on the compressor outlet portion of the turbo. Mine just came in today so I cant speak the the performance gains. I don't expect any though, I only bought it so my outlet pipe would fit better. Also may make it louder too. By turbo inlet pipe i'm assuming you are referring to the intake. The "stage 1" portion is the stock airbox and anything before the MAF. That is the restrictive part. The "stage 2" part is what actually goes into the turbo and while you dont have to replace it, i'm a fan of a metal pipe vs plastic, and it just looks better. Hope this helps.