I ran my '83 944 on the track last weekend and the engine got really loud, knocking sound. Several racers came by and said it was almost certainly a cracked exhaust manifold. I have verified when i disconnect the fuel injector on the cylinder the noise goes away.
My question is what my options are to replace it? According to rules 13.7 I can't use a 3rd party solution such as the one sold by Lindsey Racing, but I have heard the cast iron headers are much strong and available from 85 1/2 and later vehicles. Can I get clarification that I can use a later model Porsche header on a early model 944?
I suppose I can try to have the header welded/repaired but that seems like an option that will come back to bite me later. Maybe there is a wrap you can apply to the headers to close the leak. Don't know if something like that exists or not.

Thanks!

13.7 Exhaust System
13.7.1 The stock genuine Porsche OE exhaust manifold (header) is required. The stock header
consists of two separate manifolds, one connecting cylinders 1 and 4 and the other connecting
cylinders 2 and 3. Headers may be welded to repair cracks and headers may be wrapped with
appropriate materials so long as the wrap is removable. Headers may not be coated or painted
inside or outside.
13.7.2 Exhaust system rearward of the OEM header is unrestricted provided it serves no other
function than to expel exhaust gases.