Thanks. Yes, I use the tape just as you described, except the tape that worked for me was black, electrical tape. I think I needed two strips. If "reverse shim" refers to metal only, then scratch my term. In any case, if it wasn't for use of tape as discussed, I likely would have returned or sold off my Blackbird.
I hear what you're saying about using tape strips under the top cap edges. It can really improve a razor. When I searched B&B about the use of tape, I only found one member who wrote about it. Did you say anything here about your mod? Should I start a separate thread about the use of tape and shims to tailor aggressiveness?