The cabby's are also heavier so what I would suggest is look to cash in on her and try for a mk5 130bhp as the zetec engines are great and you can get the likes o pulleys, leads plugs, cams etc etc

And most of the rs2000 gear/ mods fits them too s/s exhaust, chips, and of course the most effective TURBO POWER!!!!!!!!!!!!!!!!!!!!!

But if your heart is set on keeping the cabby, drop in a RST engine or a 2.0 Zetec Engine

And if you want to keep the engine you have all I can suggest is plugs leads, cams, pulleys, air filter induction, s/s exhaust all adds up