Venom8R

How hard is it to replace headgaskets on a 96 cobra? I heard its hard since its the DOHC engine. I hope its not that but it still runs awesome. Every now and then I got to add water. The exhaust doesnt seem to be blowin any coolant but I could be wrong. If it is headgaskets i wonder if i need to replace anything else. This car has over 115,000 on it. Still runs awesome! Any thoughts? thanks yall!