I heard that I can stack it with putting a PGM axle and regulary stacks. Is it true? Are there any other ways?
That will be your easiest way of doing it. One thing to think about, some of the PGM guts can introduce vibe and wobble to the Project 2. I have used two separate sets of PGM guts on my Project 2. One played dead smooth, the other vibed like crazy.