Not sure how relevant it is, since the 2.0 8V and 1.8 20V are such different engines, but a PiperX induction, Milltek exhaust (cat-back) and remap got mine up to 142bhp, 148lb/ft - as confirmed at AmD. That's 27bhp and 26lb/ft over stock.
1.8 might benefit more since it'll be wanting more air as it tries to rev harder... strangely my mods just smoothed and shifted the entire torque curve straight up, still peaks at similar points, etc...