Just get the territory pipe and hose, cut a hole in the bottom of your air box. You can get a k&n if you like but not needed unless your making more than 300rwkw
There is an eBay seller called 1tuffxd15 with a custom xr wagon interior f&r seats and door trims in blue for $550 at the moment, might be worth a look
I would also recommend Pitlane, Mick and Bel are great to deal with. I have a bf that they did a tune only on and I have 250rwkw, just to give you an idea.
In my bf auto I put twin hot dogs in the centre pipes,stops it sounding like a tractor and when I had to have it tested (highway patrol enforced) it came in at 89db