Probably a suspension thing as already mentioned but, just out of interest, what tyres are you running? I run standard 205/50 R15s on my Mk3 but I have some nice Dunlops on the front paired with el cheapo Nangkangs on the rear. In my opinion all this does is kill some of the understeer but some people have said the car feels twitchy. That can be the problem with any vehicle dynamics problem; the human element. Engines produce nice solid irrefutable numbers but chassis and suspensions have this whole "feel" business to take into account.
S.M.