Smudo

Sales guy from Bullseyepower said that their drop in wheel "require no special tools or machinjng. Simply remove your stock wheel and replace it with ours."

However, the local turbo shop guys who rebuild the turbo and installed the wheel said that it is advised to balance it (or verify that it does not need it), because even in case the new wheel is balanced, the old shaft and hot side wheel were balanced with the old cold side wheel thus if you want to make it right, it is advisable to do the balancing. But I understood that it does not require a lot of time and the cost should not be high.

The turbo shop in the end provided a printout regarding balancing (I had also new and bigger hot side wheel and new shaft). I have no experience or relevant knowledge thus I cannot interpret it.

Voith

Agree completely with what local shop said.