Nom61, I don't wish to post anything official on the web site bad about a product but I want to share with you what I know about Cometic vrs Fel Pro.
Cometic is a niche player, they have the ability to use CNC machines and create a MLS design gasket for almost any engine. That is their strength.
The negative, MLS designs used on OEM engines use a much better stamping that lasts much longer than the Cometic design but these type are very expensive to produce and the molds wear out and have to be replaced. For this reason the Fel-Pro design is a OEM quality MLS gasket and far more durable and leak proof. The Cometic design is good but you need to know the limitations. The Cometic perfect customer is the drag racer running a odd engine, 440 Chrysler for example. They can offer this guy a better gasket that will hold more pressure. The complaints I hear are that they don't seal water as well.
This feedback has given Fel Pro MLS a hard time selling MLS because people hear horror stories about MLS and associate all MLS. Cometic MLS and Fel Pro MLS are apples and Oranges
The negative about Fel-Pro MLS, it is only available for small block GM, Big Block GM and small block Ford. The High Volume parts that cover the cost of the stampings needed to produce this level of quality. There are a lot of details I know about the designs that make a good OEM gasket quality. The Fel Pro design is as close to bullet proof as you can get. But expensive. I know the engineers and have had conversations about the testing they do. I can't put this type information out without causing possible legal flap or losing my source, so I have chosen not to but I share with you to help make your decision. Fel Pro is owned by Federal Mogul, they make pistons, bearings, piston rings and gaskets and seals. All these parts are dyno tested at some point and having OEM business helps create the funding for these dyno tests. At one point they had over 50 dyno's running full time doing development. They have less now because the new Super Computers allow testing in the cyber world and have really cut back on dyno time needed.
I like your build by the way, when will it make some noise?
I really wish I knew as much about the other 95% of these cars as I know about engine parts, I might actually get mine on the road. Oh well, money and time. Hope this helps.
BTW the Fel Pro MLS has been tested to 2200 HP in a small block GM Twin Turbo Bonneville car.