Hi,

I'm planning on buying two PPO Pro12 subs in 8 ohms. My plan is to run them in parallel to use with my PPI A600.2 (600watts rms into 4 ohms)

I don't have any experience with subs at all. I guess I'm still new into car audio.

How are these subs? What else are they comparable to ?

 

Only PPI "PRO" sub that I recall was the old flat nomex cone one's and they are excellent SQ drivers even by todays standards although their ability in terms of output is nto on par with many of the choices now available. Only problem is trying to find some in good condition. Suspension was their weak point.
I do know someone over at ECA was selling a pair of PRO12's single 8ohm coil.

 

Great SQ subs. If you're going with the 12's, make sure you go ported. IMO they are very poor sealed.