kia does not have a 1.6 that i know of what kind of kia was it out of? I think the brown injectors are to the 1.8  but they should still work!!!

The rio has always had a 1.6. The older type had a Kia (aka Mazda) 1.6 and the newest version has the alpha w/ cvvt. I doubt the older 1.6 injectors will work and/or I doubt they are any larger.

If you want to run mild boost run the 290cc from the 2.4 (older non theta) Sonata motor.

the injectors were outta a spectra or a sephia cant remember here is a picture of them they look the same as the 1.6 accent injectors dont know if they are bigger though the motor could have been a 1.8 or a 2.0 i could have been mistaken.

Spectra 2000-2004 1.8 (Kia/Mazda)

Spectra 2004+ 2.0 Beta2

Sephia 1994 1.6 (Kia/Mazda)

Sephia 1995 1.6 or 1.8 (K/M)

Sephia 1996+ 1.8 (K/M)

They are all going to look extremely similar because they are all about the same thing, a solenoid. Check the plug. That’s where the biggest diff is going to be. If the car has a common ecm such as semiens/bosch/etc the generally have the same connector on the injector. To be honest I don't know if the mazda type kia's used a common ecm with hyundai. The newer ones are hyundai cloans. If the ecm is the same type they should plug in without isse, hell I have heard of some ford injectors working on the beta. Once you confirm the plug is the same you need to check the resistance on them. If one is high and the other is low you can do things to correct that.
That is of course alot of work for nothing when you can use the hyundai 290cc's once you are under boost. They are plug in play.

I don't think you will see any real gains throwing different injectors in pre-boost. The ecm will just adjust them until it sees the right 02 readings. If it can't adjust them you get a CEL.

Also if you do manage to add extra fuel without adding extra air you will more than likely loose power. From the A/F ratios I have seen on newer Hyundai’s they need to be riched a little from idle to 4.5ish k (so you may feel a small gain at lower rpm) and then leaned out a little nearing redline (where you are at when pushing the car). Also a nice bump in spark timing would help (pre-boost), but would require a little better gas than what they currently recommended. The bump in timing would be a really bad idea once boosting...

All of the above mentioned stuff is a PITA because our ECMs fight any changes you try to make. Get an SAFC and it’ll shift around your altered signals until it sees what it wants to. I have heard a few people talk about the new Neo, saying it does a better job.

As far as stock sizing, not really sure. The only 100% I know are the beta1 at 235c and the 2.4 non-theta at 290cc.