for prices look on bavauto.com about $960 plus shipping
as far as the sound: very deed sound, burbuling is great, no vids do it justice since it sounds best while in motion. in park, it sounds pretty contained, but as soon as you put it in D, it's music to the ears. very hard to describe, if you're familiar with Remus, you can tell it's remus sound just by hearing it. (back in the day we had remus on e36 M3, sounded awesome).
as far as power: stock is not free flow and always felt very restrictive to me. with the remus seat of the pants this is what you get: more responsive, quicker off the line, smoother at highway speed, where the performance is most noticable for me is off the line and right about 80mph, then going up, has a little more pulling power than stock, but TONS of smoothness, very hard to explain.
as far as break in period: people that have remus mentioned about 500 miles to break it in, then sound is even sweeter than when you first put it on the car. they are right, i noticed the change after about 440 miles with it on. just music to the ears.
only problem i have with it: why in the hell did i wait so long to get it (3 years with stock sport exhaust )

btw: if you do install it at home, when you take down your stock mufflers, before putting the remus on, just turn on your car and see how beautiful bimmer v8 sounds with no mufflers on can you say firing up a race car? ;p