pops and bangs!

[bernhund]

My 2.5 is now popping and banging like a Le Mans racer changing down for the Esses, however I'm not at Le Mans and it ain't race tuned! So, what's up? Is it likely to be an air leak? I think the manifold gasket has gone on the rear mounting as usual. It happens every 6 months! But I generally just get a tappety sound from that. Tick over bounces up and down by 50 rpm at stand still. I think power might be down a fraction, I'm not too sure.
I've also got an oil leak, which I think might be the front turbo. I assume thats bad news but could it be related?
Expert knowledge appreciated! (Car really needs a good look over by the experts but I simply can't justify the expense at the moment, I've got some major spending to do on the house and it'll end in divorce if she catches me spending on the Nob!)