I would suggest not even using 400 mg. But, what you can do is split your dose over about an hour, or do frequent re-dosing of your total amount that you would normally take all at once. This way, more o-desmethyltramadol is produced in the liver, which is really what gives tramadol most of its opioid feel. Really, trust me on this one - you don't need 400 mg, and split or re-dosing can really make a difference. If you are very versed with tramadol, and know how it effects you that way, try maybe 150 mg, and then 150 mg an hour later. Or 100 mg, then 200 mg an hour later. Often re-dosing blunts the effect of the extra drug, but with tramadol it is GREAT to re-dose for best feeling effect. Just try the 300 mg split, or even 200 mg split would probably do the trick, and leave your mind open to the possibility that you will really enjoy yourself more than you would think. You will be pleasantly surprised, I think.