Hiya mate
I've had the ppp fitted for about 3 months now, i would say it has been an improvement better low-midrange pull, but as it is subaru approved ppp is expensive for what you get compared to other packages.
There are quite few companies offering simlar packages with more power, but important thing is your car being a 07 wrx will still be under warranty if you fit the ppp kit it will not affect the warranty.
overall the ppp is worth fitting