Bagi review how this K125 perform?

Got quoted old 2020 stock for 21550/R17 for RM250 each. It's RM100 cheaper compared to current stock

You guys reckon it's worth the savings? Read online tires older than 6 years from manufacturing date shouldn't be put in service so technically can still use?

The ps4 ride very harsh, even on a E class, can feel that the ride is very noisy and vibrates a lot. Maybe E class NVH not good enough?
Primacy 4 is similar to XM2, rides well but not too quiet also. Tested on X1 for ps4 and X70 for primacy suv+.

Sometitme people read online review see the dB number, which is measured external of then car.

Yea, Primacy is one of quietness tyres on the class. The dB number is higher than budget XM2. But that is not what we experience in car. 100k ish car have better noise insulation than econobox.

Had a 225/45R17 change to PS5 from Prime2. PS5 as a UHP is more quiet than Prime2. Not sure about Prime3.

But, I don't not agree Continental are all noisy. I had PC6 and having SC7. Both are equivalent to PS5 in quietness. And PS5, PC7 tread pattern is very smart (can see the similarity in design philosophy of both brands over last gen tyres tread) near zero noise in smooth pavement.

Having CC6, I think same as Kinergy EX, but XM2 is more quiet than both. But thr ownerships are many years apart, not like PS5 vs PC6 that I have driven both back and forth over long period. Well maybe you are right at the lower end spectrum, when come to UHP, they are very close.