hi jim,
i have both sets of headers:
the 2" are on my RB, MP head '64 fury (street car -- straight plugs)
the 2" - 2 1/8" step headers on my LB, raised port '65 satellite (race engine - angled plugs)
the step headers are a bugger to change plugs unless you have a lift and raise the car. as far as fitment, you can't beat TTI. on both cars the headers slid right in place from under the car. also remember that any under-chassis header will capture the starter. as far as performance, TTI is not a true equal length tube header. fitment is their first consideration with performance a close second. if you want to squeeze every last HP potential out of your engine then go with a custom header or something like hooker's super comp header that has equal tube lengths (but you are giving up fitment and will be denting tubes and/or using motor mount spacers to get them to fit).
on my race car i figure i wanted a set of headers that i could remove and install easily as i have the potential of breaking parts on a regular basis.