The do make boosters that work in the stock loacation, if you choose to go that way. Both have advantages and disadvantages. Stock location has the advantages of an existing mount location and keeping the firewall clean, but they tend to need residual valves due to being mounted so low, and can be hard to service due to location. Firewall mounts has the advantages of being mounted at the highes point in the system as well as easy service, but require the firewall be reinforced to allow for mouting. So it really just comes down to personal preference.
