Right, I'm knackered, sore and still have a broken car.....I think it's time for a second opinion..
I removed the exuast manifold in the cold raining weather today. Not as straight forward a job as I hoped, but eventually got it out. After a thorough inspection I couldn't find anything wrong with it. Unfortunately the one I had to test as replacement showed significant cracks so didn't swap it out, but good to see an example of one that failed for reference. The gasket that came off showed no signed of 'sooting' or breaks.
So now it's had a new downpipe, and all the gaskets replaced. The manfold-head studs came out with the nuts, so just refitted them but made sure they were tight. I supose it could stil be possible that these aren't securing properly,...may have to elimate this yet..
I'm losing faith in my diagnostic abilities so think that a second opinion would be a good idea at this point.
Basically, the exhaust "sounds like" it's blowing near to the manifold. It gets louder (deafening) as you accelerate. After taking it out for a short run after fitting everything today, I reckon the engine does feel like it's resisting acceleration which may be significant. While I haven't checked the exhaust back from the Cat, cursory checks don't shown any obvious faults. I also don't think a hole in the exhaust after the cat would produce the same symptoms.
Anyone got any ideas slightly from left field? ...or anyone you'd suggest to go to who will offer some ideas?
On the plus side I also fitted my new rear Nitrons while I was there, sweet.
