How much to cut out for fenderwell headers?

Give me a few days and I'll try and get some measurements and I'll dig around to see if I have any photos of the engine compartment before I assembled the car, and no! they didn't come with any templates. I just cut away a little at a time until I got the fit I wanted.

Just remember, with the Headmans, you will need to notch the shock mount or at least heat them and dent them.