At about 1500 rpm I get a buzzing vibration from the engine somewhere. I've heard that it could a cracked heatshield. Does this sound right? Is it easy to replace? I was thinking of perhaps getting one from a brakers yard...

Nimbus,

You should be able to get away with having it welded back up!

Hope this helps
Andy

The answer no, it's not easy to replace, since the bolts are almost certainly seized into the captive nuts, and will sheer off as soon as you look at them. The broken one is probably the front bottom one. As Andy says, either weld it back on, or you can drill a couple of holes next to the bolts and put a couple of self-tappers in. Worked for me.

Graham

do what i did take the manifold off, get someone to port it then wrap it in exhaust wrap. the resualt [more power less heat!]
i cant now touch my manifold when hot

Thanks for the info guys. I'll see how bad it is next time I get a chance to look. I think I'll have to go for the welding option, but will probably have a word with the dealer first when I take it in next...