I am thinking of purchasing the ppp package for my03 Sti and was wondering what differences i will obtain and are they really obvious when driving the car.
Also i have a Blitz back box on my currently standard Sti and was wondering if it would bolt onto the exhaust system provided in the Prodrive package because i feel that this box is far superior to theirs.

 

Timbow

Prodrive don't replace the complete exhaust (Not quite anyway) The Resonator section is left on, which is the section that the BB connects to so you'll be OK

The PPP does make a difference through the rev range. The turbo spools lower down the rev range so you are on boost much quicker. The Torque through mid range (2,3rd & 4th gears) is pretty good

You can get more power for similar money or less from other sources, but if warrany is important to you then you will have to stick with PPP

Hope this helps

PS This is how the car should have been supplied in the first place. I also have Prodrive springs on mine which you'll find you need to handle the extra grunt into corners. It goes on and on once you start

 

yes, the rear box you have will retro fit the PPP system, if you contact a majority of the dealers, they already have a demo sti with PPP fitted so you can try it for yourself before joining the waiting list [yes- not an off the shelf job].
The engine pulls really well from down low and simply keeps on going, till you run out of gears, if you let it.
PPP is best way if warranty is an issue, as this is also covered by full manufacturers warranty.