Opioids on 75mgs Methadone Maintenance

Is it just me or being on 75mg of methadone, no opiate I can get high from or feel (fentanyl is the only opioid that can bust thru my dose) when I shoot heroin, I get a rush, and a 10 min buzz, and back to sober. I talk to other addicts at my clinic who are on like 150mg methadone, and swear they can shoot dope and be high for hours, they said it was the quality of dope I had is why I only get a rush and a buzz for 10mins...but still I don't understand how I can shoot a bundle on 75mgs, get a good rush, and a 10min high...more methadone is the only thing I can get high on, or fentanyl patch...anyone out there still get high on dope for hours on methadone maintenance? or same effect like mine?

At high doses of methadone (>about 40mg), your tolerance will be astronomical... and you're not alone.