Yep have the Abbott 3"downpipe on my 9000lpt(AR ecu as well).
Giles gave me the option of the downpipe or rear box when i went there- rear box would change the note and improve top end power, but the downpipe would help with throttle response. So i went with the latter choice and he was dead right. No change in engine note that i could detect.
Would definately recommend it.
I've just had the JT 3" downpipe, sport cat, and full system fitted, and there is a slight increase in noise, well, not so much a noise, more a purposefull pulsing burble......
And it's not really noticeable from inside the car.
I've just fitted the full 3" JT system to my CD Carlsson 2.3, ditched the cat and very little exhaust note change at tickover and normal driving but on full bore it sounds great but still not intrusive. Turbo spools up faster and car performance is definitely up. It fitted easily, I only had to trim 1" off the tail pipe section to position the outlet correctly.....and it was hundreds of £££££ cheaper than Abbotts
Err... AFAIK, the Abbott downpipe is 2.5"- at least the one I had is
The gains from the Abbott downpipe are principally due to the smooth gas flowing around the bend straight out of the turbo.
I have replaced it however with a JT 3" front section to cope with the extra power I'm after. It's available from ELkparts, however if you intend to interface it with a standard system (or in my case, the full Abbott system) you need to fit a reducer and cut down the length.
After fitting it, I would say that the exhaust note was slightly quieter (perhaps a little deeper), probably because it replaced a stainless steel section.