My advice: Take it rectally.
Correction: It is a very bad idea to take substances that locally exhibit vasoconstrictive effects rectally. The price to pay could be a case of ischemic proctitis, which is potentially deadly. Both chronic rectal stimulant application (sufficient data exists for cocaine and methamphetamine, but I doubt cathinones, phenmetrazine or amphetamines will be different) and single doses can cause chronic and acute ischemic colitis respectively.
My new advice: Eat it. It's by far the best route of administration for amphetamine. The BA is very high and you won't damage the little intranasal mucous membrane surface you have (let alone your veins, with IV use not even providing a rush).
Regarding the rush with IV use: Whenever we get some street speed (usually very small amounts for weekend sessions with my wife that take place every few months), I test it with a single IV injection. If there is a rush, I know there is another major active compound in there. Even caffeine has a better rush than amphetamine. There are some stimulant phenylethylamines that can be left in the product from a sloppily performed synthesis, but it i not unheard of that amphetamine is - you probably guessed it - cut with other psychostimulants.
Another word of warning regarding IV Euro Speed: There's some really weird shit in there. Few samples get past 10% amphetamine (usually sulfate with leftover freebase). Now
some adulterants can pass through 220nm filters before falling out of solution.
Try this: Heat some water and saturate it with your Euro Speed. Draw it up into a syringe and put it in the fridge over night. You will be both surprised and disgusted of what you are very likely to see.
I've been meaning to make photos of this to post them here, but haven't gotten around to it.
I suspect the substance in question to be some form of cellulose. It will completely dissolve, pass through whichever filter you use and fall out of solution/recrystallize. The substance is a crystalline needle structure. Needles can be over an inch long.
Example of what happened the last time I did this: I did NOT heat the water, so the solution was not even saturated. I did not even put it in the fridge either (both these things will increase the likelihood of this process taking place). However when I looked at the syringe the next day it was stuffed with crystals (cellulose?). It was actually hard to squirt the stuff out of the syringe.
Now imagine that shit goes into your bloodstream. I've seen it happen many times, but this last time had me so disgusted that I haven't IV'ed speed since. Just don't shoot it. No rush and extremely taxing for your health.