I am currently running hks wastegate (40mm) w/ 5lbs spring in it and I am also running greddy e-01 electronic boost controller.
I am boosting 13psi on my td07 turbo. My question is, if I am going to change the spring rate in my wastegate to 10lb spring, will I need to retune??
Or will my greddy e-01 automaticlly adjusting and keep my boost @ 13psi??

 

It should adjust to it.

 

what if i would change it to a larger wastegate say a "44mm or 50mm" w/ 10lb spring, do i need to retune (or is my tune will be all f'ed up??)

 

those HKS 40mm don't do so well on rotaries from my own firsthand experience... I'd like to see a graph of your boost curve

If you want the best boost curve, your boost controller will absolutely need to be adjusted. Guaranteed. On a typical external wastegate setup, the electronic boost controller settings determine how much pressure is applied to the top port of the wastegate. That extra pressure essentially stiffens up the wastegate spring. When the wastegate spring itself changes, a different level of pressure will need to be applied to the top port through the EBC. Most EBCs have a self-adjusting capability, but the boost curve will still be best if the controller is tuned.