The Larini sport cat is a popular choice. Many have reported good results and no codes. I have one I bought used and after some track days it is a bit worn out. It could catalyze well enough to keep away the code with gentle driving for a while, but now throws a low efficiency code pretty quickly.
Eliseparts sell a unit, but it only works with their header. Both pieces are full stainless, appear to be very well made. Shipping and exchange rate are going to bite you. The cat is GBP395, the 4-2-1 NA header is GBP695, the 4-1 SC header is GBP675. Plus shipping charges and maybe customs. I haven't seen any feedback on these, you might look on the UK forums.
The 2bular headers and exhausts are very well regarded here, and he makes sport cats (200 cell) and race cats (100 cell) as well. I think most of the users here go with one of his decat options. I have the silenced decat, but haven't had a chance to run it much yet. Again, you'd take a hit on exchange rate and UK shipping.
Quicksilver, also in the UK, make a full stainless header-sport cat package for GBP1080. They have a US dealer, Evans Automotive, so you may save some import costs dealing with them.
PTP Ltd, again in the UK, sell a 4-2-1 header and sport cat in stainless for only GBP612. That price is so low, you'd be well advised to get some reliable feedback as to the quality and effectiveness of the pair.