I have a new to me 1988 LX 5.0 with a brake issue. I don't know much about the car itself and its my first dive into a fox body. I've had a 66 Mustang for 30 years so I know enough to be dangerous. The LX has had a 5 lug swap with cobra brake calipers. The brake pedal goes to the floor and there is about ZERO brake response. The engine is supercharged, and it idles at around 7 inches of mercury. I'm guessing that's not enough to supply the booster properly. However, if I understand how the booster works, low vacuum pressure would not equate to a pedal that pushes to the floor. If the car was only low on vacuum then the pedal would be hard to press, not easy, correct? While I may indeed have a booster issue with low vacuum my guess is I first have some hydraulic issue with brake lines or the master cylinder. Without the car running or any mechanical advantage I should be able to get a firm pedal if everything on the hydraulic side of the system is working the way it should. For my low vacuum pressure my thought is to add an electric vacuum pump but I'm open to ideas on that. Someone please point me in a direction. Thanks.