I did mine in stages so got the cat back part first then a new downpipe with sports cat which I then had a custom decat and downpipe made using the downpipe so I could swap my standard cat and decat come mot time. Have a look at AmDessex.com and awesome-gti.co.uk or .com.
Would reccomend doing it in stages then you feel and hear the benefits of the parts you change, doesn't use all your money and I found that it's kept me interested in my car, had it coming on to 4 years now and still look forward to driving it ;-)
