Changing valve springs on vxr8

[snowwolf]

Is it a good idea to change the valve springs after a certain mileage ? If so can the be done in situ ?

[ringram]

Depending on cam and springs they should be changed.
Yes you can do in situ.
I was told after 3 years to change..

Need to pressurize the cylinder or some other method.

[gsd2000]

http://www.briantooleyracing.com/tools.html

valve spring tool and valve holder adapter for an airline