that was close - i was about to order a 4.2 A8 exhasust as a temporary thing from A8 parts! they have had a dig and come up with a good condition S8 system now.
That will hopefully stop my horrible rattle (although i suspect its the insides of a cat - despite them looking pretty new and just going through an MOT)
This will give me a system off the car to chop around - i have a couple of ideas.
1. The middle box is going around the welds where the pipes go in/out, so i it would make sense to split and bypass this.
2. Repair the rot and put a pair of butterfly valves on a 45degree T just before the back box. Wire theese to a switch inside as per 'sports mode' on the latest RS4's, and to the 'squirt mode' on the shifter. as per theese from Ratsport -
http://shop1.actinicexpress.co.uk/sh...ut_trimmed.jpg
But they are £200+ each, and I would obviously need two. Thats too much to go splurgeing on playing around with a rusty old exhaust, so i would need to find them for about half that.