When to change valve springs?

[EyesofThunder]

Was wondering when most people consider changing valvsprings? My 1UZ-FE (VVTi) has stock springs and I am at 176k miles. I will be doing a timing belt/water pump this summer, but wonder if I should budget in new springs. I don't spin it high all the time, but would like to keep it in top running shape.

 

[XR8tt]

I guess it's up to you..I can assume they up graded the springs on VVTI ?
Lighter valve train..

 

[EyesofThunder]

Springs don't last forever but at what point should I be concerned with them?

I guess it's up to you..I can assume they up graded the springs on VVTI ?
Lighter valve train..

 

[XR8tt]

I guess the miles its done and the type of performance you expect ??
It's a bit how long is a piece of string question..
Often an engine in good condition with some TLC, as in new springs brings
back performance esp in higher rpm..