He might be referring to one of those throttle controllers that don't do much
I have seen a heel of a lot of M35's with them attached (sites and auctions mainly).
Don't really know what else he would mean, unless he means an aftermarket TB like a Mine's or Impul unit.
64,000Y + shipping + supply of ECU? hmmm, I think I'll try HKS first.
Would definitely be good to remove the restriction though
G-zone are good to deal with (comparatively) and take into account all the mods you tell them, but it is still an educated guess and you will need a piggyback of some kind to take full advantage of your mods.
Oh, and word of advice, don't ask them the same/similar question twice
EDIT: Having said that, if I hadn't already bought my Fcon harness, I would definitely be interested.