Any gear boosts RBC production to some degree.
The most is Anadrol(Oxymetholone). It was created solely for this purpose, to treat children with sickle-cell anemia.
After that, its test, EQ, and some others....but they won't come close to Anadrol.
Also, some people have genetically high RBC levels. Mine oscillate between 8.0 and 9.0, but I have seen some endurance guys with RBC's in the 10+ range.
Thats just AAS though....you cannot kill yourself with AAS in terms of RBC's producing so many blood cells, that your hematocrit levels(Viscosity of the blood) begins to rise dramatically(Normally in the 60 range or so), and your blood begins to coagulate, and you have a myocardial infarction.
Only EPO is powerful enough to do that........reason why I won't go near it with a 100 ft pole.
Normal heamtocrit counts are between 40 and 45. For AAS users, depending on your dosage and choice of gear, they osciallte between 45 and 55.
(Btw, hemtocrit = Total volume of SOLID components in blood plasma / Total Volume of Blood Plasma).
Mine normally always stay in the 50 range as long as I stay reasonably well hydrated.
Fonz