It should pull more than 120, but I doubt it is anything to do with the air filter.
It could be you air flow sensor (MAF) on the way out.
Get a VW/Audi/Skoda/Seat specialist to check you car for logged faults on the ECU using vagcom etc. If the MAF is knackered the boost is limited by the ECU thus making the car slower.
I forgot to plug my MAF in once after doing some work under the bonnet, the car was very slow and would only boost to 5 psi, no fault lights appeared though. When I plugged it back in though all was well.