sounds like ur just not running enough boost, if youre running 6psi and u say the wastegate is opening and is boosting to 6psi but wont rev its probably coz once it hits 6psi the wastegate opens and the turbo cannot let anymore air in, seems pretty simple, just try boosting it up to about 10 - 12 psi see what happens. i know on my mates stock turbo charade on low boost it stops revving at about 4 grand....

when boost comes on can u feel the turbo spool up like can u actually feel the boost......
my mates 4agze rolla does the same thing u boot it and it reads 8psi but seriously just goes NOWHERE it is useless i could beat it on a push bike....but at the moment we are still searching for a problem......hes one for ya....do u have a blocked exhaust system ....that could be causing the prob

Quote: Since atmospheric pressure at sea level is less than 15psi [absolute],.... to be reading - [minus] 15 to 20 psi would be a good trick as this varies between a perfect vacuum, & 33% more than a perfect vacuum. Not even deep space is that good.

The guage is probably showing 15 to 20 inches of mercury [hg] of vacuum, which is more normal.
When you remember that NA engines run to more than 4,500 rpm at nil boost, i am bewildered why ANY engine would perform badly as a result of having ONLY 5 or 6 lb's of boost. That logic defeats me.

Fuel pressure?
How are you compensating the fuel press in relation to the boost pressure?

tried the ute again and now its not reving at all i couldnt even get back up the slightest hill
i was holding my foot about half throttle and it just wasnt reving and now it wont even start
any more suggestions????

When was the last time you put some LPG in the tank? The guage on the tank itself - how much pressure does it read?

there is plenty of gas in the tank

Are you drawing thru or blowing thru the gas research carb? what converter you running?? b2? Have you got a balance line to the converter?? if blow thru, have u tried it norm aspirated??? do you run a oxy sensor for tuning..... just a few questions to get me up to what your playing with

Cheers
Dave

timing? if your timing is not set and running more retarded than it should, the boost will not really do anything. i know this is the case on EFI type setups, as one of the things they do to keep the motor safe in "limp home" mode is the computer pulls a stack of timing out. have you checked that?