Hi, Limesmoke. Apologies for late reply - not exactly at my best today. I blame the (lack of) drugs 8)
As mentioned above, I do have a fair bit of experience of IV MDMA so I'll try to give you a coupla pointers as to how best not to do yourself a nasty. You say you have previous IV experience of other drugs so presume you are well aware of the risks of using any drugs intravenously and also know the basics of technique, sterility and so on already and skip the IV Drug Use 101 bit. Mostly...
Would be good to get a few more details of your prior IV drug use experience - what drugs, frequency of use (occasional treat or daily habit or somewhere in between) and so on. More detail the better cos it's a bit of a risky business and I could do with knowing a bit more about your previous experience, tolerance and anything else that could make a big difference - any medication you are on, for example. There are a coupla things that would be good to know if possible:
1) You say you are used to IV drugs but you only mention that you started injecting speed about a week ago. Do you have prior history of IV use of speed or any other drugs? Or has it just been this last week or so you've been shooting speed with no previous IV use?
2) From your post it sounds like you haven't used MDMA at all for some time. Weeks? Months? Years?
3) I presume you have tested the powder you have to confirm it is actually MDMA, but would you have any idea of what level of purity it is or what cuts are likely to be in there too? Bit of a longshot that one but you never know.
Dose seems to be your main concern and - to be honest - it's gonna be mine too. I have only ever shot crystal MDMA that - although not pure (tested at around 85% pure) wasn't cut either. The fact you say you have powder does concern me a tad cos there's no way of knowing the purity or cuts. Unless you've had it tested which I'm guessing is not the case. I'm guessing that it would be of reasonable purity but cuts could be a concern so micron filtering would be a very good idea if possible cos I doubt it would have been cut with IV use in mind. Cotton will do at a push but a micron filter would be much better if you can.
600mg between two should be plenty for the night - especially if you've been shooting speed but haven't used MDMA in a while. I would suggest around 50mg or so - certainly no more than 75mg absolute max if you have little tolerance. It is of fairly good quality 50mg should be a fair whack and 75mg would likely be pretty damn strong. 100mg (as in my report) takes no prisoners. Not even folks familiar with IV drugs are always keen on IV MDMA so it really is better to err on the side of caution even if it means not being as blown away with the first shot as you would like. It doesn't last too long IV so I suspect there will be a second (and probably a third) before the night is out. I often shoot a slightly lowish dose first myself before going for a big one cos it can be a bit of a shock to the system
I'll try to check back on this thread later cos I'm sure I've missed stuff out, but feel free to PM me if you want too. I am crap at replying to PMs in timely fashion though - you have been warned :D
Also, my trip report on IV MDMA may be of interest as it has a few details I'm sure I've forgotten -
IV MDMA (Mostly) – Experienced – Molly Dearest (Mon Amour)