When I bought my car it had manual brakes. If I remember correctly all I did was unbolt the m/c from the firewall and gently pulled the m/c with brake lines attached and all, dropped the booster in place, bolted it in and reconnected the m/c to the booster. The reason I beleive I was able to install the booster without removing the m/c was the fact that the entire project was very quick. I remember being shocked at just how quick the whole thing went. The other odd thing I remember was installing the longer (or shorter) push rod then ultimately going back to the original one. All in all it was a very easy project and resulted in huge benefit. IMO power brakes and power steering are a must!