how high can siv go

I am really suprised how high SIV has risen. When it was just above $3 it was excellent value with a grossed up yield around 10%. Now its in the $6's its yield is just above 5%. The debt/equity is quite high at 148% and the question is can it still continue to grow at the same rate as it has in the past to justify a P/E of above 15. I think it might be time to take some profits and reinvest in TGA.