Neither...
#3 B&M short throw (yes), KKM intake, Miks or custom heat shield, Dual-mode Damper instead of the SHO Shope pullies, don't get the Superchip if you're doing more mods eventually, H&Rs (yes), get new struts too, 40k miles on the stock ones = they're shot (meaning you put H&Rs on them, the car will ride like crap), Konis or ST200 struts would do fine.
As far as wheels, it's all a matter of weight. Stay under 21-22lbs per wheel (stock is 20-21) and it's unlikely you'll see a performance decrease. (be it 17 or 18")
Download the BAT catalog for hte Contour. (www.batinc.net)
-J
