Music to my ears. It's worth it to go all-out for yourself. I mean, if you don't take care of your injection process, who will?

Even if it's just once, your body deserves your respect to the best of your ability.
I would encourage you to try buprenorphine, anything to get you off that tar man, I know how it is out here in California and trust me, even if you get quality tar, you're doing a number on your body, even with a micron filter. I would highly recommend you checking out Opioid Replacement Therapy, absolutely try buprenorphine, just make sure that after induction, you start rapidly cutting your dose as low as possible, under 8mg if not 4mg.
Of course, Ideally, you'd want to get down to 2mg, it would make getting off of the drug exponentially easier in the future if you're reducing your dose from 2mg-->1.5mg-->1mg-->0.75mg-->0.5mg-->0.25mg--> Done, rather than something more difficult such as maintaining at 24mg and having to taper for a super long time, having to taper -->12-->6-->4-->3-->2mg, and then the same sub-milligram taper. The lower you get, the harder it is to taper, the more you're going to feel it when you decrease your dose.
YMMV, best of luck to you. Please try buprenorphine before methadone, methadone should be your very last line of treatment, that is seriously the last thing you want to do.