You should shift before the redline, The guys that built your car put the red bar on your tach for a reason, so you dont float a valve or spin a bearing, In regards to the 350Z he must have not been paying attention a 350 would SSSSMMMMMOOOOKKKKEEE a stock civic. I had a d16z6 in my civic it liked to be shifted at 6200 rpm even tho it redlines at 7200 when i shifted it was in the powerband for greatest acceleration.