I recently had the pleasure of testing out Vit's new boost control amplifier: VitTuned Boost Solenoid Amplifier (aka PWM Booster) - Boost Control/Vacuum Blocks - Products
This device boosts the signal for the boost control solenoid circuit as the signal from the stock ecu is not powerful enough to properly operate the solenoid. This gives much more consistent boost control, even more effective quick spool, and no more up and down boost through the pull like before:

Look at the insane torque increase in the mid range, nothing else on the car was changed, just the amplifier and an adjustment of the tune:

My impressions: The car feels fantastic, even more powerful and notably more torque than before. I cannot even explain how quickly the car gets to 0 vac and begins to build boost, you can see in the graphs how much sooner it builds boost, but this does not do it justice, you have to feel it and experience it. The boost control is more consistent so the car pulls consistently through the gears rather than boost going up and down and thus power going up and down something that after enough seat time you can definitely feel. It also makes the boost control more predictable, no more 1 duty cycle = 1 psi or sometimes 2 psi, it seems every 3-4 duty cycle creates 1 more psi, so you can be much more comfortable adding duty cycle to your boost tables. Ultimately, this device makes the boost controller work the way it truly should, and it is fantastic!

The install was about as simple as they come, 1 power source, switched or unswitched. I chose an unswitched source - the fuse box in the bay as the booster is only taking power when the solenoid is active, which will only be active when the car is running. Vit also said it's power draw while off would be so small it would not matter, seems to be working just fine for me, car starts right up every time with no hesitation, even quicker than my GF's bone stock 2006 civic ex The rest of the install includes two ground wires that on the 8th gen si can share the same ground and even the same ground ring. Then you have one wire go to port b2 which is the boost control output on the ecu, and finally finish it up with the two boost control solenoid wires going to the screw terminals on the amplifier itself. Easy as pie. If you can install a turbo kit or even something as simple as the boost control solenoid, you can easily do this, and you can easily add this in after the fact as I did. Took no more than 30 mins to install and I am known for working slow