Most people seem to be injecting a couple inches to each side of the belly button. I've found I get welts when I do it there but I might be doing it incorrectly. Injecting into the love handles works best for me.
I've done sub-q shots of test C 200mg/cc, test E 250mg/cc, and EQ 500mg/cc. I've found it best to only do .5cc in one spot, more than that and I get a lump. Never experienced any pain from any of these, just a lump if I do over .5cc. I've only done them into my belly.