The makers claim "over 2psi of boost and about 15% power increase at the
wheels". Its unclear whether the device increases boost as the revs
increase, by controlling the pump speed. Neither do they indicate what
happens to the air-fuel mixture ratio, or how the output from the MAF sensor
is "modified" to (maybe) satisfy the ECU program.

True forced induction systems (turbochargers and superchargers) increase the
boost as the revs increase, and the ECU is programmed to adjust the mixture
and timing accordingly. In addition, the compression ratio is lower so the
forced system can compress more air-fuel in to the cylinders. When the
normal n/a compression ratio is used, the amount of boost is limited or else
the engine will have detonation and hot spots in the combustion chamber that
can cause burned valves and pistons. True forced induction systems typically
have around 7-9 psi boost.

What this device seems to do is blow more cold air into the engine, and
hence more fuel, and relies on the ECU to sort out the mixture, ign timing
and hence the emissions. The problem is that the ECU relies in a complex
formula that includes rpm, O2 and MAF and coolant temp readings. If the
induction pressure, rpm and O2 readings are out of sync, you may have a bit
more power (at what rev range?), but the fuel ecomomy and emissions will be
messed up.

The clincher is that the manufacturer says the device can removed when you
need to have the car serviced at the dealer.

Don't waste your money.