I know Blacksunshine, I was just messing around. :biggrin:
Domes are what makes the coolhead a "head". It is a 3 piece system, domes, top and bottom plate. All 3 parts are a must. It replaces your old head. Your old head has domes built into it and is all 1 piece. Water flows around the top of the head to cool it off. Same as stock, only the water chambers are bigger and it is all billet so it runs cooler. Now the size of the domes are up to you and the mods, gas, and what you intend to run. Most go with 21cc domes. This is better than stock, but still safe in most areas for compression.
If you do not plan on getting your motor worked, and you have not reason to change compression often. The alternative is have your stock head decked/shaved to drop the compression. It runs 50-80 bucks in most cases.
IMO it is worth buying a cool head. Even for simple mods like timing, heat is added and the cooler the head, the better. Go with the NOSS Head. No changing out heads bolts.