12 would be max with storage upgrades and 8 with transformer upgrades as GT limits them to max of 4 per stackYour memory serves true. The ind. centrifuge makes four rubber per sticky resin, but it requires four sticky resin (sixteen rubber, for those of you counting along) and takes a minute and five seconds. Whereas an extractor with twenty overclockers and four energy storage upgrades (assuming you properly power it to get enough packets, of course) will give you three full stacks of rubber before your ind. centrifuge has even started to pass the halfway point.