I'm not a doctor but I got laid at a Holiday Inn express.
When you 'smoke' weed you get two primary methods of transport into your Cannabid receptors. The first one you experience is that of absorption though the walls of your mouth etc into your blood stream. As the smoke goes through your mouth down your esophagus and into your lungs. The next stop is into your lungs where it's directed to your blood stream.
The first part is relatively small, in fact you'll notice people who don't inhale, don't get high. The second is what gets us good and toasty.
Shooting up would just go direct to the blood stream. IMO if you feel a need to shoot weed you've officially had WAY too much to smoke.
If you had a cut in your mouth then you probably could have a slightly higher absorption during the inhale but I doubt it would make a significant difference in your high.
Stick with smoking or vapeing. There's really no need to get there any faster.
I'm absofuckinlutely fried right now...