A new booster can be faulty. That happened to me. 19" is plenty... Mine works on 11".
Are your soft lines on the front brakes in good shape? If they're 20+ years old, you may want to renew them. This could make a difference. It helped mine considerably.
Last edited by Bronze Bird; 09/17/1707:54 PM.
I'm a hobbyist. Not a professional. Don't be hatin'!