Boring out the Throttle body and HP gains?

I've been contemplating boring out the throttle body. Has anyone done this or tried this? What kind of HP gains am I looking at? I'm assuming this is also going to have to be re-tuned with the extra air going in?

Also since I do believe that the both of the 3 engines have "variable valve timing" (aka. V-Tec for honda owners or VVTi for toyota)  is there a controller for that the will be compatiable with the 2.0 engine? I know honda has a v-tec controller i was wondering if there was similar?

Thanks guys/gals!

Ive been wondering about boring out my TB as well, i found a member on cardomain that has it listed as an upgrade, has'nt said anything bad about it but then again hes turbo, also you cant re-tune our cars w/o a seperate FMU, there is no controller for vvt nor can you out cams or camgears in it.

what is an FMU?

I believe he's referring to Fuel Management.
 
No matter what bolt on parts you put on that engine, the fuel mapping in the computer doesn't care.  It currently can't be tuned unless you go to a piggyback or standalone fuel management system.  I think it's way more hassle than it's worth.  Either go turbo, or don't waste your money on any upgrades as you'll spend a ton of money and still have a car that's relatively slow.