Cams are easy to explain, lift=Horsepower, duration=rev range, higher the duration the higher the revs required before they start working.
Pon cams don't have enough lift available for the amount of duration and the gains suffer because of it.
I'm getting 400kms out of a tank in an r32 Gtr that has had the factory ecu remapped, so I'd be taking it to another tuner cause this one has got it wrong
Should also be making a lot more then 164kw