Will my 5.7L run?

I'm getting very close to firing up my 05' Hemi since...well...since it was pulled from the 300C years ago. I've got my wiring sorted out, fuel lines ran, fluids in the transmission and motor, and it's looking good. The only thing I'm curious about is...I have no exhaust on the motor other than the SRT8 Jeep headers... my question is will it run with no signal from the upstream O2 sensors? and if it will, does it enter limp mode? Go rich like crazy? Purr like a kitten? Anyone else been in a similar situation?

Thanks in Advance!