Not sure about exi but vti has got rocker rollers. Open the tappet cover and confirm yourself.
Regarding oil, then why company doesn't recommend 20w50?
There are people who are using 0w20 without any issues. I am using 5w30 since a long time. Tappet noise is normal on thinner oil.
Just use a semi-synthetic 5w30 or 10w30. Its perfect for this car.