Disagree with above. No Electronic Boost controller will cure boost creeping due to inadequate internal wastegate size/flow control. Something as simple as the increase in turbine flow from a 3" exhaust added onto the back of a TD05H will often cause it to no longer be able to keep up.
If your factory internal wastegate is failing to divert enough gas from the turbine wheel once you have reached your desired boost level either running a boost controller or not, then an external wastegate could be an option to cure it. Externals have the benefit of being larger to be able to bleed off more gas, the diaphragms are larger allowing it to more accurately actuate the valve and finally assuming you have plumbed it back in further down the line, there's an added benefit of not having merging gas flows right next to the turbine wheel in the O2 housing - which improves response due to less turbulence.