Lowering springs ruin mk3's handling very quickly, your shocks are probably shagged.
Dont know bout shocks but i know the springs are. Diamond hell had a look at them when the front was polybushed and he said they were <insert proper word here> touching together, basically they were fooked.
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If you put a decent set of shocks/springs on or coilovers, I gaurantee it would feel like a new car.
My personal preference is shocks and springs(koni/Eibach), for both ride and handling.
The only downside is looks