When I wrote earlier that a bundle of snakes exhaust system is worth 30 to 40 bhp, that's under racing conditions, i.e. unmuffled. Mufflers alter the dynamic of an exhaust system tremendously, there's no guarantee a bundle of snakes will add anything, I'm not inferring they don't make more bhp, but exhausting through mufflers the gains will be less than 30 bhp. But they do sound bitchen.
A well designed collector covers a multitude of sins in regards to tube length, so when long tubes are difficult to fit into a chassis, it becomes more important to provide a generous collector. This is where the majority of Pantera headers fail, in an effort to provide long primary tubes, they leave no room for a collector of any length at all. This is where Pat Mical's headers differ from the others, and why you've seen those headers recommended so many times here. His headers are also beautifully constructed, but all that craftsmanship comes at a price. Again, if your exhaust system has mufflers, its hard to predict just how much gain primaries of the right length, or a well designed collector will provide, if any at all.
In my opinion, chasing every last horsepower in a vehicle that is not raced regularly in amateur racing classes is a waste of money. I would rather see a Pantera with a relatively quiet exhaust system that is driven all over the place regularly, than a Pantera with a bitchen open exhaust system that is only driven to local car shows. I like driving my Pantera and I don't want to do anything that hurts its drivability, that's why I settled for the GTS exhaust system. But that's just me.
By my comments I do not intend to cast dispersions on your plans for your Panteras. However each of us decide to use our cars is a personal matter, and I support each of you in your passion for your Pantera.
I love the sound of a good set of 180's too.
cowboy from hell