Raising his tolerance aside, he may STILL HAVE SOME SUBOXONE LEFT IN HIM!
6 months of 4-6mg a day? Do the half lives man...if youre someone who bupe takes longer to eliminate from as well, its really an AVERAGE 36 hour half life, meaning your shoving X more mg into your body before even half of the first dose is gone. meaning you could have even MORE than you'd imagine (or know using a 24 hour half life).
Example: you add 4mg to 2.5mg, you get 6.5mg, cut that in half you get 3.25, but! If you haven't even made it to the hl yet (36 hours lets say for you), you really are at like 4mg when you redose ANOTHER 4mg, meaning now youre at 8, and once again you DONT make it to the HL, meaning its 4-5mg when you redose with 4, giving you effectively 9mg suboxone in you, and again and again....get the idea? you could have a HIGHER BLOOD LEVEL OF SUBOXONE THAN YOUR DAILY DOSE!
Obviously this was a very very rudimentary example, not taking into account BOA, how you dose (eg 1x a day or 2x smaller doses), whether or not you 'fucked' with your meds (eg. took extra one day to get high). But all of that not withstanding, the fact is you could still have enough buprenorphine left in your body 9 days later to block something as meager as a perc.
This is why I feel it is vital for anyone on suboxone to see a chart/graph of their dosing, when their blood levels level off, and simply be able to view firsthand just what it looks like when they take X amount every day at the same time, of a drug that has a mean half life of 36 hours...the overlap of suboxone dosing can be INSANE! You MUST maintain daily blood levels, by either consistently taking it EVERY SINGLE DAY (not once fucking with it, and it will level off after weeks) or find a dosing plan that will create a stable blood level (figuring out when to dose ecach day and how much of your dose: eg 4mg in the morning 2mg at night).
After all the research i've done, I am a very large proponent of once a day dosing, until you get to the sub 2mg range. and even then if you can manage 1x a day all your dose vs 2x a day half your dose....still better from the #s i've crunched.