Thank you for your replies fellas, all very interesting. Just to clarify, i'll not be using an intake or an uprated cat-back, just the hardware mentioned above - it would be great to get a nice figure at R-Tech (using the rs4 valve) then post the result here to show that expensive intakes and expensive cat-backs are really not worth it, so saving a few bucks.
Jeez, i'll be chuffed with 300bhp lol, even the standard ed30 is fun at 22-something bhp
Thanks all...!