Downpipe Advice
 

I am replacing my downpipe as I have mentioned in an earlier thread. I will only be replacing the downpipe at this time, and not any other part of the exhaust stream, and I will still need to run with the cats installed when I do change the entire system. But, in the meantime, I am looking at a 3" vs a 3" divorced downpipe. Will I notice a performance difference between the two with the rest of the system stock? If so, how many HP do I stand to gain from each?

I fitted a down-pipe as the photo below, this takes out the first cat but leaves the second one in place. You will defiantly notice a huge difference in acceleration. Also you can see it passed the UK Exhaust Emissions Test last year with flying colours, (or colors as you guys spell it)
http://i17.photobucket.com/albums/b5...f/downpipe.jpg

http://i17.photobucket.com/albums/b56/cirgriff/Mot.jpg

I am also thinking about replacing the turbo outlet at the same time if the price is right. It looks like this will provide a little more get up and go. Thanks for the input.