I don't know if it is just me, I have the PST drive shaft. It's a quality built piece but I notice a vibration. It's acceptable at low rpm ranges but at 5th gear 4000rpm, you can feel it ! It vibrates though the seat then up to my butt. The feeling is like sitting on a message chair.
I installed a diff brace and that increased the vibration even more so I have to take it off. To ensure the diff brace is causing the vibration so I installed it to my friends BRZ and he doesn't get the vibration
I ended up put the stock one back on and the vibration went away ! I am not sure if it's me or my car or something to do with the shaft !
Does anyone has the same issue ?