Clive.....what you are lookin' for may be
electronic or "in the chip"......you may need to
up grade or change your chip settings on the
940t....call ipd and chat w/them.....they can give
you a 2nd opinion.....or...try www.turbobricks.com
and look for a thread on boosting the 940...lots of folks
will help over there...good luck !!

The control switch is behind the drivers knee panel, under the steering
wheel. But, there may not be a switch there at all. Some models didn't
include it, so in that case, it is probably surge. Check Turbo bricks for
specific models. If there IS a switch there, you can carefully dig out the
glue, and re-adjust the screw to cut off later, but...take care.

RS

Surge happens when  the compressor forces more air into it's turbine side
than the turbine is capable of handling. For instance if you turn up the
boost via a bleed or G Valve, and are asking for 16 hypothetical lbs from a
turbo that can really only handle 12 psi, the compressor will be forcing
more into the turbine side (or surging) than that turbine can handle. The
effect is that the car seems to be stalling, or briefly lurching. It can
repeat a few times in quick succession. If you can get a hold of a
compressor map for your specific turbo, you can see what the safe and
reliable PSI range for your turbo is. You may be able to get 20 lbs right
now, but if you are running out of fuel, or getting compressor surge, it
might be time to turn it down a bit before you melt a piston, or get a
bigger turbo.

It's a rare b230ft that will reliably run 20 psi all day without some fairly
hefty mods, although I know guys who run around 18 without heavy mods. It's
do-able for sure, there are crazy Swedes who get 700 hp, setting it up as a
drag motor.  But get ready for some serious $$ if you want to extract that
kind of power from a 4cyl Volvo block.

I have no knowledge of a B200 engine. To be honest, I never heard of that
engine before tonight, and thought is was a typo. I continue to learn.

RS