k03 or k04

Would these fit a mk3 ibiza cupra? looks good quality but whether its gives any gains not sure...

This is from a post on Audi-sport that I am sure many of you would find interesting of a question sent to Borgwarner who make the K0 series of turbo's The Question Can the K03 turbo (5303 988 0011 or 5303 988 0053) be directly replaced by the K03S (5303 988 0052 or 5303 988 0026) in...