Had a very productive day today - got up at 5am this morning with a view to do a lot of driving up to Manchester from W. London. The plan was to drive to BCS to get a powervalve system fitted, then popped in to see Rick at Unicorn, who is 35 minute drive away, to make some tweaks to the map he sent to me earlier to account for the new exhaust as well as do some general air/fuelling health checks. Before all that though, ended up taking advantage of the deals from LVS Racing and bought a REVO CAI as soon as I woke up 
To say that I'm extremely pleased with the new exhaust system would be a monumental understatement - it's freaking awesome!! The guys at BCS all clearly take great pride in the product. I'm not an expert in exhausts, but this thing looks like it will outlast the car many times over - very high quality product with much attention to detail. Best of all though - it sounds amazing! When people say that powervalve is like the best of both worlds in terms of quietness and raw noise, they are not joking. I spent most of the way home messing about with it and loved every minute of the journey
It has two modes:
If you are gentle with the throttle, it is very quiet with a slight, but pleasant raspiness to it, with the low frequency sound slightly subdued. You can happily potter about town or on the motorway without drawing any attention to yourself. I can't say that in this 'mode' it's quieter than the standard system in terms of volume, but it is much more pleasant while cruising on the motorway or gentle driving. In-fact, you can't even hear it on the motorway due to the frequency the sound, which 'melts' into general road noise! It's an odd feeling - the thing feels more silent than my previous sline A4 or the S3's OEM system on the motorway. This might have been an issue with my OEM system, but I found it to drone a bit and after a while did get a little intrusive. My wife even commented on how annoying it was to have to listen to it all of the time on a long journey. Anyway, this is the "stealth" powervalve mode
The other side of powervalve reminds me of my old, slightly tuned Suzuki GSX-R 600 with a stubby 2" straight-through exhaust can - freaking loud and screaming! As soon as you are less gentle on the throttle and on boost, the backbox is bypassed using a 3" valve and your car turns into mental rally car. As soon as this happens, people will turn to look, children will start to cry, leaves fall from trees and risk of avalanches is greatly increased in distant mountain areas... well... maybe not, but the sound volume greatly increases, gets deeper, much raspier and the whole car becomes a very different animal. With the s-tronic box you also get much more pronounced, nice little pops on gear changes. It's addictive!
It takes getting used to, as the 'mode' you're in is directly controlled by the fast pedal. Mash it to the floor/change down a gear or two and prepare to wake the dead. Feather the throttle gently and progressively and no-one, but you, will know that your exhaust has been messed with.
I will admit that the choice of system was made mainly to address the sound of the car, with power gains in second place. Build quality is also an important factor I can't comment on the power gains for now, as I'm yet to fit a few additional bits and map to get to Stage 2+ power, plus I never had a chance to do a before and after dyno run. I guess we'll see at the next RR day All I can say is - the car feels like it has much more grunt low down and in mid-range as overtaking is much more effortless now... and fun!
@BCS Nige took his cameras and mic to my car and made some photos/videos of some drive-by runs after the system was fitted, so I'll post those up once I have them (if I'm allowed).
Finally, a huge thanks to @Rick @ Unicorn Motor Dev. , who tweaked his original Stage1 map to deal with the addition of the new exhaust. I enjoyed seeing the map moding magic happen and hopefully I didn't annoy you too much with my many questions
To say that I'm extremely pleased with the new exhaust system would be a monumental understatement - it's freaking awesome!! The guys at BCS all clearly take great pride in the product. I'm not an expert in exhausts, but this thing looks like it will outlast the car many times over - very high quality product with much attention to detail. Best of all though - it sounds amazing! When people say that powervalve is like the best of both worlds in terms of quietness and raw noise, they are not joking. I spent most of the way home messing about with it and loved every minute of the journey
It has two modes:
If you are gentle with the throttle, it is very quiet with a slight, but pleasant raspiness to it, with the low frequency sound slightly subdued. You can happily potter about town or on the motorway without drawing any attention to yourself. I can't say that in this 'mode' it's quieter than the standard system in terms of volume, but it is much more pleasant while cruising on the motorway or gentle driving. In-fact, you can't even hear it on the motorway due to the frequency the sound, which 'melts' into general road noise! It's an odd feeling - the thing feels more silent than my previous sline A4 or the S3's OEM system on the motorway. This might have been an issue with my OEM system, but I found it to drone a bit and after a while did get a little intrusive. My wife even commented on how annoying it was to have to listen to it all of the time on a long journey. Anyway, this is the "stealth" powervalve mode
The other side of powervalve reminds me of my old, slightly tuned Suzuki GSX-R 600 with a stubby 2" straight-through exhaust can - freaking loud and screaming! As soon as you are less gentle on the throttle and on boost, the backbox is bypassed using a 3" valve and your car turns into mental rally car. As soon as this happens, people will turn to look, children will start to cry, leaves fall from trees and risk of avalanches is greatly increased in distant mountain areas... well... maybe not, but the sound volume greatly increases, gets deeper, much raspier and the whole car becomes a very different animal. With the s-tronic box you also get much more pronounced, nice little pops on gear changes. It's addictive!
It takes getting used to, as the 'mode' you're in is directly controlled by the fast pedal. Mash it to the floor/change down a gear or two and prepare to wake the dead. Feather the throttle gently and progressively and no-one, but you, will know that your exhaust has been messed with.
I will admit that the choice of system was made mainly to address the sound of the car, with power gains in second place. Build quality is also an important factor I can't comment on the power gains for now, as I'm yet to fit a few additional bits and map to get to Stage 2+ power, plus I never had a chance to do a before and after dyno run. I guess we'll see at the next RR day
All I can say is - the car feels like it has much more grunt low down and in mid-range as overtaking is much more effortless now... and fun!@BCS Nige took his cameras and mic to my car and made some photos/videos of some drive-by runs after the system was fitted, so I'll post those up once I have them (if I'm allowed).
Finally, a huge thanks to @Rick @ Unicorn Motor Dev. , who tweaked his original Stage1 map to deal with the addition of the new exhaust. I enjoyed seeing the map moding magic happen and hopefully I didn't annoy you too much with my many questions
….. Many thanks
They don't do any exhaust for the 2L TFSI A4 
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