Hello Surendran,
The Pen tips are not interchangeable between generations so it means you don't have to worry about the pressure levels. (Meaning you cannot place an older tip on the newer ones). If your pen is one of the newer ones with the 4096 pressure support, then just make sure the tips you buy are compatible, which was the Pen that came with the SP4 and after!
Regards,
Cristhian