Im running a Dawes device at the moment as a temporary measure.
This is what they look like...
clickable thumbnail...
They are £40 and are fine if you have something like an Apexi S-AFC like i have which can be set up to deliver more
fuel at various points across the revs to keep the mixture rich enough.
This is the cheap way of doing it and like i said only temporary in my case.
You would be far better spending £150-350 on a decent electronic boost controller,
which will control the boost well and not allow any spiking,
and getting it set up properly along side something to keep the fuel mixture right also.
Greddy Profec b 2 seem to be the most noted to be user friendly and good at holding the boost.
Matt