i love hella. i used to be a var junkie but good stuff is hard to find for me and then i found the ph's from needto. i need to keep my weight in check so i love rockin the hella, never used katana yet tho. and from what i read ppl are off setting them like weeks 1-4 hella at whatever dose is appropriate for your body, and weeks 2-6 katana at 250/250/250/250. with those extra 2 weeks of katana solo cutting you up real nice. which was what i was planning on running bout 6 months down the road. i havent heard of anyone not saying to stack them together yet.