if you want more low end torque the b16a is a terrible engine with limited options...really with regards to low end torque the old adage - no replacement for displacement - is the best and most effective way to gain such...this would be a b18b (teg ls/rs/gs) or b20 short block for much more torque and then put on your b16a head and get dual purpose...or just get a b18c long block

the s/c will be your best hope as its belt driven and will give immediate assistance at lower rpms...turbos unless they are really small and are ball bearing equipped won't help much with the lower end but will help in mid and higher ranges...nitrous will help a little but it'll run super rich (lots of gas, not a lot of air as cams aren't pulling in air, plus nitrous) at lower rpms fouling plugs often

if you are cheap...you can always improve response by gutting the car...less weight means your lack of low end torque doesn't have to move as much mass