Smoking with a spliff isn’t the most efficient means of administration, changa will probably be a better route to go if you do want to. A spliff containing 50mg spice won’t get you very far in my experience, maybe try 1–200mg. If you are smoking it to yourself it would probably be best in a one-skin to get it smoked quicker.

Oh yeah, spice in spliffs makes your fingers smell vile (in my opinion, there seems to be people out there who don’t find it objectionable).