I have a friend who is a GM of a Triumph dealership. He initially told me that the Arrow exhaust for the 07 S3 would be full Ti, probably cost $2000, and was good for 8-11 hp (I think he had it confused with the Arrow full Ti exhaust for the 675). I spoke to a parts guy at the same dealership the other day and he said the Arrow exhaust was stainless steel with a Ti silencer and cost $1200. He could not give hp or tq figures.
I called Arrow and they said the exhaust was specially built for Triumph and any hp or tq numbers or dyno charts would have to come from them. I left a message on a Triumph PR guys voicemail but have not heard anything back yet.
I was looking through The Magazine of Triumph today and saw that the Arrow exhaust was worth 4ps. I Googled ps to hp conversion and found out that they are almost equal, 1ps=.98 hp. WTF!! Arrow, a well respected maker of exhaust systems makes a full system for the 07 S3 and it's only worth 4 hp! I can probably get 4 hp by removing the precat from the oem header, coating the full pipe, and installing a BMC air filter. To say I'm disappointed is an understatement. Even the Zard full system makes 6 hp.
Devious, bro it is up to you to make a decent header...no pressure!?