does any one know what the ratios of the rear diff are on a uk turbo 2000 and a blobeye wrx 2004?

 

2004 wrx has a 3.54 rear diff. Not quite sure about a uk turbo 2000.

 

is possible to change the crown and pinion?

 

uk turbo 2000 3.54 too mate

 

As said both 3.54 as long as the box hasnt been changed. Check your box is a TY754VN1AA or 2AA. If so its def 3.54 the "VN" is the telling part of the code. You can change the crown wheel and pinion but by the time you set it up and buy the parts your better off buying a 2nd hand one there are loads out there and not expensive.