I have the same reg as pictured on my Hemi also. I only picked up about 8 hp with the pump and mine also make 10in of vac. But that was mainly due to that I run an old school std tension 1/16, 1/16, 3/16 ring pack due to being a street car. Others results will vary from engine to engine.

1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.