When do you need to change valve springs?

[white-t-type]

At what point do you need to change the valve springs? Is it when you change the turbo, or do you only need to change them after a certain amount of time. I plan on doing a few bolt ons very soon such as alky, a turbo, and downpipe, etc... and was wondering what all I would need to change internally in the engine to handle the extra upgrades. I currently have an Accufab adjustable fuel pressure regulator, walbro pump hotwired new coils with msd wires and a front mount intercooler. I am wanting to upgrade to a 6152 turbo. Any help would be appreciated thanks.

 

[Just a Six??]

If they are 20 year old stockers then they need to be changed out. They get weaker over the years & that hurts performance.

 

[XLR8]

If they are the stock springs, I would replace them. Also may want to consider replacing the timing set if it is stock.