Td5 manifold stud replacement

[GBMUD]

Before I re-map my Td5, I thought it might be wise to remove and modify the manifold, replace the gasket and fit long head to manifold studs. Rather than just get my wallet out and buy a ready made kit, I thought I might make my own.

But what size/length are the existing studs, and where should I look to buy decent quality replacement studs from? I would rather have all the bits at hand before I start.

Any other suggestions?

Thanks

Chris