the dawes device was cheap, (i had the "race" version which had a lighter ball bearing inside, allegedly made it spool up faster, but when you think about it, nothing other than a change in the design of the turbo could actually do this, never mind the boost controller. it is v simple to fit v small, buti had it stick open a couple of times and had to take it to bits to free it off and re build it (only a 20 second job mind) it would hold 1.5 bar of boost fairl well, but there is only a fixed bleed hole in the top to allowhow fast it is allowed to build boost before it controls,

the beuty of the 2 valve system is that it allows the rate of boost increase and the max boot level to be both ajusted , indipendantly of each other.

my car is off the road at the moment so haven't actually tested it in anger and does need puttin on the rollers for a good run up/down the revs and boost to check that the chip is fuelling for the boost that is dialed in on the regs.