So i got tired of my manual boost controller not letting me get any higher than 7psi above stock. My turbo is efficient up to 16-17 psi, and since i was only able to max out a 14, i had to do something about it. There are two ways to do this. Either get an adjustable wastegate for $100 + dollars, or do what i did.
I pulled my MBC apart and found the spring inside. I took it to home depot and found antoher spring that was slightly smaller in diameter, and slightly thinner metal. I then cut it to the same length as the stock spring and slid it inside the stock spring so that is was now dual coiled. I threw the MBC back together and sure enough i now have a boost range from about 14psi-21psi. You could probably just use a stiffer spring rather than double coil it if you can find one that is the same size as the original spring. So simple and cheap yet so effective!
CAUTION! Doing this can make your boost controller more unpredictable and cause boost spikes. Know your turbo and fuelling limits before doing!