I have a 1993 RHD FD seq. twins, no engine mods.

When WOT or even half throttle you can hear it boosting but nothing happens. Actually you feel a rush of air under steering column. The BOV whistles, but when under any kind of acceleration it actually deaccelerate and bogs. Sometime it starts to backfire pretty good. It has 124,000km and the motor was replaced at 110,000km. The boost gauge would climb to .8 bar and drop, wouldnt keep any boost

I swapped out the hoses from the Y-pipe, intercooler pipe. There is however a few vacuum lines that were not hooked up but after checking the diagram i got them placed back in the right spot. I tested the vacuum tank and it seems to be good.

 

try seaching your problem , there are lots of common problems . the map sensor vac hose comes off , the cats clog, boost leaks ect.

 

Its not big issue, mostly people know about it. If you have no idea who to get rid of it then simple go to the expert mechanic who solve it in a few mints.
Heavy air pressure create boosting noise, check pipe of exhaust.

 

My suggestion is:
Change all hose.
I spent a lot of money searching for solve this problem in my car.
At last i solved changing all hoses vacuum and pressure.
If possible put a silicon hoses. they should have a longer life.