your question does not make sense to me. I may not be familiar with B15's but i am assuming your car is like mine and there is only one plug for a computer. running 2 is nonsense. what you are suggesting is a piggy back system or using a SAFC. these are tuned with your original computer to run your injectors and monitor the maf. to my knowledge you could run a jwt ecu and it will work fine with your smog equipment.(if JWT makes a ecu for the b15) the problem is that turbo manifolds dont have places for the smog equipment to bolt. unless you buy a smog legal kit your not gonna pass smog legally in cali. there is a visual test and i dought you will even pass the sniffer at idle with 370cc injectors. i imagine you would need to do some fine tuning with a safc to get it to pass the sniffer. it is even gonna be hard to pass it with a smog legal kit.