before/after numbers were inconclusive as the wrong pistons were installed (8.83:1 versus stock 9.8:1) and as we later found out the builder did not tighten one cam bolt and the cam walked 20 degrees or so. we didn't expect really any changes as no power additions were made with the rebuild.
quite a while if I remember correctly, although not driven day to day. customer realized he was pushing the envelope and was awaiting engine failure. he actually got away very easily, it could have been far more catastrophic.
Yes I know I blew my mach up....did he ever get the car running correctly?