The 4th gear sound about right, i mainly use it to maintain speed, and keep consumption down, it has poor acelerating capabilities...

now that you got it you should do the standard service... oil, oil filter, plugs, points, condensor, air filter, new coolant, and stuff like that... should make it run smoother... also new brakes, fluid, drums if needed, cylinders... and so on...
only thing i can think of with weight reduction in mind is the spare wheel, who needs it

(and bumpers, if not needed for MOT...)
p.s. didnt know that sciroccos had a turbo wersion? is it aftermarket or orig?