I've decided to go with what I know - yes, another Maniflow system.
I drove down to Salisbury of Saturday to speak to them and they now do stainless steel. Cost is marginally more than an expensive PowerFlow system, but I'm sure Paul Harvey will back me up when I say that there really is no comparison on quality.
I was frankly appalled by the crap PowerFlow wanted to weld together - the the bends reduced cross sectional area by around 30% which according to them wouldn't lose me power! lol. They also wanted to weld the 2.5" bore pipe onto a back box with only a 2.25" inlet!
Maniflow showed us one of their bends and I can honestly say that you can not see any reduction in cross sectional area on the bends they do. Myself and Paul were extremely impressed - well worth the 60 mile round trip. My current Maniflow exhaust is mild steel and has lasted 3.5 years, so I'm pretty happy with the standard of built to - a stainless one should lass much longer. Oh - Maniflow don't have a BS lifetime warranty that you can't claim on anyway! Maniflow cover everything for 3 years, including welds.
I'm asking for it to be made very quiet - three silencers in all. All silencers will be straight through types, so there will be a very minimal loss in power.
They will be welding on the Vectra Tail pipes that I acquired a while back - so it will have a nice standard Vauxhall look to it too.
Fingers crossed this will be on the car in time for the TV SP day and will maybe give a little more power as my current exhaust of blowing and the baffles have had it.