I saw something about this somewhere and was wondering where you could GET a larger TB for a Series 1, or how much the TB would have to be enlarged to show a gain?
Would you need to reprogram the PCM for a larger TB, and could you avoid this by boring the stock TB?

You won't be able to 'get' a larger throttlebody.
You could grind out the center post and smooth transitions out with metal epoxy.
The maf will be completely exposed so some afc tuning would most likely be needed.
Or you could just cut out half the post like Dame***(forgot spelling) did.
And the only way your gonna make your plate size bigger is having a machine shop bore it out and get a new plate.
You probably shouldn't go much more and a few mm over and remeber you have to match up your */c to the same bore size of the TB.
Sucks there'* nothing readily available but it'* still possible.

Some are installing the larger throttle body from the Northstar engines, 75mm vs 68 mm. Several kits out there but $$$. Will need reprogramming of the computer, higher flow cam or rockers, etc to take advantage of the increased size. For serious tuners only in my opinion.

those above kits are only for the series 2