I'm considering a few mods. Not sure if ill do cams, or cams and bore cylinders with new pistons, or cams, cylinders/pistons and head work. I know I'd need a larger throttle body (and injectors) with the last option comprising head work but not sure if id meed the upgraded throttle body when doing the cams and cylinders/pistons option.  My bike is a 96b softail with usual stage 1 mods. 

My questions are:

At what point are larger throttle bodies (and injectors) reqd?

Given the cost of the throttle body kits which usually include injectors, is it a better value option to have the oem Harley throttle body modified? And if larger flowing injectors are required, purchasing them separate to add to the modified oem throttle body?