Stupidly, replacing the exhaust was one of those jobs that I thought I could do really easily whilst I was waiting for other parts but it just ended up being at the bottom of a long list of things to do and was a bit of a pain.
Whilst removing the carbs I noticed that the standard exhaust was connected to the manifold by only 2 studs, the other one having been welded in and then broken. Of course I was pretty pissed off but at least it explained those mysterious headaches! After a lot of metal bashing and pulling I got the old one off and put it up for sale on Ebay where it made about £15. The chap came to pick it up on his way to Canley Classics and we talked Spitfires for about half an hour. He showed me some pictures of his beautiful MkIV which looked to be in stunning original condition. Certainly one to look out for in the future!
So that left me needing a new exhaust. James Paddock (www.jamespaddock.co.uk) had a special offer on so I picked up a stainless 4 branch extractor manifold for £105.
When fitting it I noticed that the flange that attaches to the cylinder head wouldn't mount up at the same time as the inlet manifold. I eventually solved this by grinding the excess metal off the flange and mounted it up. Only then did I discover that the pipes that run under the car were touching the bellhousing. A bit of bending later and there was about a millimetres clearence.
I'm looking into the posibility of using a bit of heatwrap on the exhaust and I'm still trying to decide what to do about the rest of the system!