you can get softer sidewall tires... Hankook V8rs... RE001 is a lil hard.. PS3 still ok ok... but if your ride is lower i think it is a lil hard too... too bad Hankook V12 does not have your size...

that size should be over the 3% of the OE size...

The bumpiness might also caused by ur new suspension setup , the Eibach .
The spring rate u using is important . 
I doubt it by changing the tires spec will eliminate the problem

well everybody knows cheap is good?!!
and the expensive depend on our drive routine
either we are the light or heavy road user.

Lets begin with how to read the Tyre specification on the side wall of tyres.
1. Tyre brand name

2. Pattern or model code

3. Tyre size

4. Service description (Load index & Speed symbol)

5. ECE or EEC type approval number**

6. ECE noise approval

7. North American recall code

8. Date of manufacture code

9. UTQG quality rating

10. Maximum permitted load (USA)

11. Maximum permitted inflation pressure (USA)

12. Denotes tubeless construction

13. Safety warning

14. Direction of rotation (Directional or Composite tyres)

15. Rim fitment instruction (Asymmetrical or Composite tyres)

16. Denotes extra load tyre construction

16a. Denotes reinforced tyre construction

17. Position of tread wear indicators.

**(C & U regulations stipulate all tyres used in the UK must carry an E number)

no it is over the 3% rule compare to the OE size... which will affect your Speedometer & ABS functionality...
PS3 should be slightly better in comfort... but those tires is more towards performance and the sidewall will not be soft... V12 is performance tires but it is soft... so does most of the Toyo performance tires...

prefer Hankook V12 coz Toyo's tires wet grip is so so only...

BTW stick you 15" if you still need a lil comfort... That is the reason why i did not change my Vios's (yr 05) rim to 16"...
16" onwards the ride comfort suffers then price is expensive, plus lowered i can feel the ouch on the butt...
took a ride on a lowered new Vios J b4, with lowered Titan Spring (front) and Titan shocks/abs all round... he uses 195/55 R15 Federal 595 Evo... the ride is slightly bumpy but still bearable for me...
if you want a lil comfort change back to 195/55 R15, but i duno your comfort tolerance so i suggested u to take PS3 1st instead of RE001 or GSD3... used Hankook V12 b4 on my stock ride, it gives me comfort but don like the handling and the Hydroplaning is not up to my expectation maybe our car too light... now on PS3 think overall is better...
is up to you now...

PS3 i don think u will gain any comfort on 16"...

if you calculate properly the diameter of 195/55 R15 and 205/45 R16 is not much difference...
so your car height is not affected much...

well what is your tires now??? sorry did not know what model are you using now...
maybe the tires that you are using at 15" is soft also... the pressure maybe is too soft too... how many PSI are you on during 15" (195/55 R15) tires...

try to lower ur pressure a lil... but mostly 16" setup tire pressure need to increase a lil also (35 PSI maybe)... depends on your preference... just make sure it is not under inflated... or the shocks and springs is too hard... coz Vios is a light car, the more harder the shocks are the more bumpy will be...