Ok, sorry I know this is an old thread. Although, I feel its necessary to say that it is most likely purely subjective as to whether clonidine will dampen your stimulant high. Due to the factor of using different stimulants that produce varying ratio's of DA to NE. For example, this is stating what you prolly know, but dexmethamphetamine(which is what a majority of street ice is with a minority ratio of levomethamphetamine which has purely peripheral effects similiar to levoamphetamine.) releases DA to NE 1:3 respectively, i believe more centered in the VTA, but as well there is certainly activity in the Nucleus accumbens. However Dexamphetamine(dexedrine, what 3/4 of adderall is) releases DA to NE at a 1:5 ratio. That being said some speed users enjoy higher amounts of NE than others, and others have different thresholds and what not of what they like, and whats to much. For me, I find I like the norepinephrine body buzz up until a threshold where too much equals the tweak outs we all know, and that adderall because of the levo amp is really notorious for. Getting to the point, I find when using methamp cloinidine fucks up the initial rush bc the physical stimulation is nice for a few hours and not overwhelming like adderall. However, with adderall sense my amphetamine tolerance takes about 35 - 40 mg dexamp to get me speeding, i have to take 45-50 mg of adderall, and that much levo amp will make me so tweaker acting and irritated extremely anxious eetc.. So clonidine really helps in that aspect to give me some relief from the craziness so i can enjoy the dose. Dexedrine and meth, however, it takes away from the necessary amount of NE, due to alpha- 1 agonist effects , so that threshold amount of stimulation for me to feel "Up" isn't reached although I often still feel the euphoria. But the overall effects are still there. So you just have to try, and see. I couldn't get through when I have to use addie when my malicron. dex 15mg er, and street speed is gone without those once thought useless clonidines. Some like some don't, but I highly suggest this to anyone that has a high tolerance to amp. euphoria, and doesn't have access to meth or straight dex, because at first when it only took 20-30mg of addie too speed there wasn't an issue, but due to desensitization(downregulation) of D2 receptors, and modulation of the DAT NT in general, paired with the weird phenomenon of sensitization to the psychomotor peripheral effects of amps, it can be a savior at canceling down the peripheral effects of the amp that grow worse over time accompanied wit the addiction... Sry for rant hope this helps