I've been doing weekly injections with a 23g pin for the last 6 weeks. I draw with a 20g. I ran out of 23's (will have more next week), so I used a 20g to draw and then switched to fresh 20g to inject.
God damn, that hurt like hell. I've heard that some of you guys have injected with stuff as large as 18g.

You guys are better men than I.
The Test Cyp does a good job of lubing the 23g needle. I don't think it can lube the 20g as well.
Sonny