Did u mean MBC? because that is ilegal for stx as well, cobb does have a stx ots map u could run.
i would recommend improvements in this order,
#1 Tires, ( star spec, rs3, rival or equivolent) #2 Wheels 17x8 as light as possible ( cheap alternative check drag wheels on discount tire 17x8's <$500) #3 Alignment at least 2.5 degrees of negative camber in front (doable with $20 camber bolts or plates if you go to coil overs) slight bit of toe out all the way around. #4 coilovers ( ground control sleaves with koni sports works great cheap, or megan or bc's work cheap as well but ride worse) Spring rates look for 400-600 in front and 500-700 in back, rates depend on your prefernce what your looking for in the car. #5 brake pads hawk hps/hp+ work great cheap rotors r fine, #6 power adders and weight reduction wherever possible.
Hope this helps!