I recently won a Prodrive exhaust for the Brera S on eBay and had it fitted this morning. My car is a MY 2008 car with only 20K on the clock.
The car before had noticeable hesitation in 1st gear and a flat spot around 2000 rpm in 2nd, i;d pretty much got to the point where every time I set off I was slipping the clutch and short shifting to get in as high a gear as possible to just get away cleanly.
With the Prodrive S back boxes though there is NO hesitation, NO flat spots, the car has NOT been remapped.
The Prodrive boxes are also considerably lighter than the stock items and sound great, not boomy, a nice deep tone.
I had a quick drive through Huddersfield centre out towards Brighouse and back to work and car was completely different, response is better, low speed dynamics vastly improved.
The old exhausts that came off rattled like nobodies business and when you shook them up and down large chunks of carbon fell out of them.
From this I can only think that the issue with the 2.2 hesitation is purely down to the design of the rear boxes.
I'm not sure what a remap would bring to the party but at the moment I can't really see why I'd want one.
I'll be at NICN this month and hopefully will get an ex Spider 2.2 driver (SpiderMonkey) who had the hesitation and a remap to corroborate the above.