We had this lovely Mitsubishi Evo 6 come in, the ower was complaining about a vibration at around 4000rpm which shaked the whole car
We diagnosed the problem being the shaft bearings beginning to fail. So we installed a shaft delete kit. There is a slight shake still present but this is to be expected when you remove the balance shaft, the vibration is far less than what the failed bearings were causing.
Also there was no oil pressure loss
We fitted a HKS decat-back exhaust while the car was with us which you can see in the picures below