I think my power master has gone because it is basically imposible to stop my car now and their is a brand new accumulator their. I would like to go a different route and also get rid of the drums in the rear. Any suggestions
Anything on vac? Or another way that i can go all disk?
Search through the forums for opinions. I have a thread going on right now asking almost the exact same thing (powermaster/rear disc)...

Some guys like vacuum brakes, others hate it. It's probably better than the powermaster at least. Another option which ties into the power steering system is Hydroboost brakes, which supplies a ton of pressure to the brakes and is generally thought to be the best system. You could also go manual brakes with no power assist if you've got the leg strength to stop the car yourself.

There are plenty of rear disc conversion kits out there, kits like Baer and Wilwood are going to cost a lot. You can find decent kits for $500.

just did my 2nd swap to vaccum on a buick. pm me and u will spend 50 bucks for a swap. 3 hours of labor ---the work sucks doing it though.

Hydroboost conversion

Buick never installed vacuum boosters on turbocharged cars. A pressurized manifold is the opposite of vacuum, and vacuum boosters need 20" of vacuum. They don't work on this car. The Powermasters have given up a long time ago. The hydroboost is superior to all. It needs no vacuum , and no 12v motors that can burn out. The car performs and handles better than ever. The Hydroboost uses the same pedal as the Powermaster, saving a lot of work in changing that out.
I believe so, but not really sure. Bottom line is that resolution of a problem is always second-hand to first time success. I prefer first hand success myself. Too many resolutions of a problem indicate that something is not right in the first place. HTH