You want to be careful like Madog11 said. Buprenorphine is only a partial opioid agonist, however, there have been cases of Overdose, and in each of those cases, the suboxone/subutex was combined with temazepam or some other benzo.
Also, I'm not sure what your tolerance is like, but 4mg is quite a high dosage of bupe (which is extremely potent, partial agonist or not) to start off with if you don't have a habit. If you use opiates infrequently at this point, .5 mg should be enough to get high.