a k&n filter is only worth around 3 kw,
running one with the xh snorkel will only realy see you gain 5 kw at most, but you get better fuel economy from it, so is worth while. also the initial purchace of the k&n will be off set by the fact you can re-use the k&n one (clean then re-oil).
you are better of getting a k&n pod and enclosing it in a custom made box with a cold air feed.
the filter is worth 3kw or so still but the drop in inlet temp is more noticable, more torque across the rev range (not a tyre frying gain but is noticable), and the rule of thumb is for every 10 degrees of inlet temps you drop, you gain 1 kw.
another option is to run a ef upper air box with a au lower air box, have the k&N filter inside running a au series 3 xr8 inlet snorkel, then run a 3 inch convoluted pipe from box to throttle body.
if you cant make it ur self get ur husband to do it
i am sure he'd love the chance to tinker with your car. :)