STOP... You don't need to inject Cialis... because it doesn't really breakdown into anything in your gut... Cialis has a high enough absorbtion rate, that you can just take it oraly and you'll be more than fine...
Their is only so many time's that you can prick yourself with a needle, before you get some scar-tissue build-up... Scar tissue build-up in the penis means ED/Peyronies (wich their is no known cure for).
And with all this injecting, you have a higher chance of infection AND, this cialis might not even be sterilized well enough for injection (wich you can just imagine getting this problem, causing a part of OR all of your cock to be amputated). But hey, you will make history and people will remember your for years to come of the person that lost his penis, trying to find the ultimate Penis Enlargement "recipe"... LOL
Think before you start injecting cialis in your penis... If you have to, just take more cialis than normal, ORALLY!