Depends on what you want from the car and the pipe tbh.
If you want large gains in hp and are mapping etc,sports cats and de-cats are going to make the most difference, but will cost you as well. decat means changing it back once a year for mot.
Maf and lamda sensors can play up with sports cats etc. Lots to think about. If you're staying pretty standard or just a stage one map then pipe work like I had done should suit the car well.
Mine is more responsive now, sounds great too, seem to hear the turbo spool up more as well, sign the air flow has increased I think.