Cost and function here. A simple bleed valve will work....set it and forget it.. Not real pretty though but cheap. A good manual boost controller like the HKS type. A little more $$ but pretty solid. Both of course need a good accurate boost gauge so you can dial them in. Then the Cadillac, the EBC. These come in various types and functions but you will fork out the dough. Do your homework before buying one of these. You should read up on all of them so you are dialed in to what you want them to do.