The STi PPP cat is a pretty ill fit ( wrong hangers & leaves a gap at the flanges from my own experience). Go for the Ninja or the TSL. I have opted to go TSL again as I have heard of a few NInja DP's failing the MOT emissions test.
My new TSL job was £410 delivered ( took less than 24 hrs to arrive!) but it really is a work of art and is fitted the the TSL 333 bhp packages. The only issue is that you'll need a classic centre section to got with it. Effectively you'll be running an entire classic exhaust system that fits your new age.
My advice, is take the risk with the Ninja ( lots of people are happy with them) & save money or pay for more quality/less risk e.g TSL.
The Prodrice CAT is 200 CEL, the Ninja is 150 CEL and the TSL is 100 CEL ( the latter being the more freer breathing)
Hayward & Scott aslo make them but they are £500+ !
Cheers
Cal