[DMXF]

That cost-benefit issue rears it's head quite often. I think you can find 45mm chokes to drop right in your 48IDA's. I've heard of guys running stright tubes for chokes at the 48mm bore size, although anything approaching that is not be design and may have side effects.

From numerous dyno plots I've seen comparing carbs (in general) of different sizes, going larger in choke/bore size to a point increases power at all rpm's from at least 3000 on up (so mid range torque and HP increase). Dyno results don't tell you, however, about driveability off idle up through 2000rpm, which suffers as you go larger. So, yes, in most cases smaller carbs will "feel" better in traffic use. If you're up to the challenge, getting the larger carbs to run smoothly at lower engine speeds will give you a stout ride. You would probably have to go real big, beyond practical, to start decreasing power across a wide spectrum of engine speed. But you can try different things for yourself and let us know how well all this fits with your configuration.