I have a dohc zc motor swap in my 91 SI and it seems to be running rich (low gas mileage, fuel smell from exhaust, mild black smoke when under harder acceleration) I am running a mugen 4-2-1 header w/ o2 sensor, high flow exhaust, and short tube w/ cone air filter intake with the stock SI ecu. Any recommendations (rev limit @ 7500 right now.) Z dyne will reprog the stock ecu just wondered if there were any other options out there. I may run a turbo in the future.