I think I put most of my long-term ideas on this subject in
Loved Up vs. Fucked Up. But, I'll put down a couple of things here that have just surfed their way to the tip of my tongue.
First, by snorting speed the mucous membranes in the nasal passages and oesophagus absorb more of the amphetamine that comes into contact, than by swallowing the speed. Correspondingly, the drug acts quicker. By swallowing, more of the drug is lost through 'first pass effects' in the liver, and is absorbed less efficiently through the GI tract. Often people find if they take speed orally they need up to 2-3 times as much to achieve the same effect, though this is not true in all cases.
Second, with regards to the speed seeming to be weaker, or wearing off quicker, I think that is due to a couple of reasons. With a "speedy" pill (meaning one that actually gives an orange result to a standard Marquis test, not just one that isn't MDMA), sometimes it is apparent that the head rushes, and body buzzes last for an extended amount of time. This could be due to the presence of a good amount of meth/amphetamine, pseudo/ephedrine, caffeine, or any other dirty stimulant that is thrown into the mix. I think I remember a post by Biscuit about Dexies that dealt with this a little, (and yes I just tried searching for it but after nearly 20min waiting for one search to process I decided that this slow computer sucks far too much arse) I'll try and remember as much as I can. With a clean CNS stimulant (for example dexamphetamine, or d-amphetamine) there should be little peripheral nervous system stimulation, ie. the boundless energy is there, but there is little noticeable headrush or dangerous blood pressure increase. With speed on the other hand, these peripheral effects are much more noticeable due to a slightly different mechanism of actions (ie. speed, l-amphetamine as compared with dexies, d-amphetamine - I think).
My impressions of the physical effects of speed are that if you have a decent amount then you experience a real rush for between 15-60 minutes, which then fades away leaving you clear headed and full of energy. The rush subsiding could be mistaken for the speed 'wearing off' but from my experience the CNS effects from the speed will persist well into the next day. While there is no alteration of consciousness or feeling of the rush, the energy and lack of need for sleep are present for ages.
While the quality of both speed and speed-based pills can vary widely, I think that it's one of those situations where different people perceive different effects from the same drugs. I guess it's up to you what you prefer, I know that personally I'd rather try to measure the dose by taking speed alone, then add in any other alteration of consciousness in a 'controlled' way (is there such a thing?) by adding other chemicals in known doses, particularly when mixing with previously consumed chemicals. For example if you'd had some MDMA and then wanted a speed pick-me-up, I think it would be better to take speed, than drop a speedbomb because you just never know what's in them that could combine badly with what you've already had. If someone gave you a speedbomb containing DXM or viagra, it might make your heart race and blood pressure rise and get you 'fucked up' under normal circumstances, but could do so at dangerous levels if you've already had other amphetamines etc.
An alternative to a speedbomb for a good cheap fun night could be the lovely combination of speed, alcohol and thc. Care is advised, so you don't get too messy, but I reckon a few cones and lines work wonders. You get just as fucked up as you want, and then the goey stops you from falling asleep too.
BigTrancer
------------------
I don't want to sound paranoid, but just consider how much of what you're writing could help send you to Jail.