Your from auto to manual that's what the really problem is. Auto has 7 gears while manual only have 6. It's all about the gear ratios. Auto will of course feel torquay than manual at lower gears. If you have bicycle experiences you know what I am talking about.
That being said, this 370z manual transmission is so hard to launch fast. That has been brought up here again and again and again and again if you ever do some researches... The most negative 6m driver out there on this forum has claimed he has been smoked by Toyota Camary(or the same class) in many places and weather conditions. (
*cough jungleZ cough* ) So beaten by an eclipes is not too bad. LOL. Next time, try not to race with anybody on a public road. But if you have to, rev it to 5k and dump the clutch see if the eclipes can keep up with you or not. But do it at a drag strip.