all your answers are YES they are great motors they respond well to mods the only draw back is that they dont have much mods out there IE.... cam gears are off a B16 (JG) CAI well the intake is a diferent distantce from the TB to the frame (only by a hair) little things like that the exhuast ports are OFF they dont line up right so no matter what header u get its gunna have to be ported! Those are minor hang ups i would go DOHC ZC anyday over a B16 just becuase of the cost alone i have a ZC in my 4d that got totalled so i'm pulling it and putting in my NEW 91 STD hatch (4spd) and i'm putting in a Si Tranny
and i'm also swapping my Teg brakes on my STD hatch also its VERY worth the money i would stay D series if you dont have alot of money and u still want some good HP and MPG