If you installed the Bosch 996TT valve it is the same basic crappy unit that has been used in the 965-993TT and 996TT, Audi and VW products for the last 15 years. yes, they have been updated but the design is limited.. That's why I mentioned the Forge or Bailey unit..

When you start messing around with manual controller or EBC you risk damage due to urge to crank the boost up. Again, the spikes you are seeing are/is not correct sustained boost.

If you aren't happy with the current boost control buy a tial 46 wastegate... Boost control will be more crisp.