If you have a hard pedal, your booster is leaking. 15" is not bad, but not great. Another option is to build a vacuum reservoir. Run the vacuum to a canister, then out to the booster, like whats shown here from Jegs. http://www.jegs.com/InstallationInst...70-99590-1.pdf

 

My vote is simply for a broken booster......

You should have enough vac for your power brakes to be better than pretty good.

Check for a collapsed vac hose feeding the booster also.

 

KMatch I tried your suggestion and there was at best a small difference. Since the booster is under warrenty I am going to return it and get a new one. Then I will go from there. Thanks everyone for you advise.