catalytic converters for ford ea

[BRADMAN]

hey all
ok today i did some shopping for some extractors & high flow catalytic converter.
i got some many different stories it wasnt funny.
anyways are pacemakers the best choice?

secondly
what is the difference between the 2 different types of catalytic converters. ie comb vs the metal one.
i want longest lasting while still having good thruput.
so which one of the two types should i choose.
thanks