Based on road test data from back in the day, it appears that the factory was fairly optimistic on the quoted engine horsepower figures.
The carbs, distributor and cam timing are different on the US cars from the ROW (Rest Of World) cars. You can make a significant difference in the performance of your 2.0L engine by changing the cam pulleys.
I have the Dellortos, 107 cams, high compression forged pistons, ported head, re-curved distributor, green dot HTD cam pulleys, fully balanced rotating assembly and a lightened flywheel in my S1. It dynos out at ~175Hp.
I bought my S1 in pieces with a blown engine and gearbox so I never had an opportunity to drive it stock. Hence I can't report on the original performance.
While it doesn't have any where near the torque of my 2.2L cars, I still find it very enjoyable to drive. And it loves to rev. The only downside is that the lack of torque means that it must be kept up in the rev band to move quickly.
I hope that you enjoy yours as much as I do mine.
BTW: What color interior do you have? Is yours the Tartan upholstery?
Mine is a mint green full leather.
'84 Turbo (x2)