If your alternator needs extra help around idle, maybe. But that's only if you have A/C, power steering, a large stereo, ...
Otherwise, If you need the extra air for cold starts and warmup, just use the thermometer valve. The Z31 has a 12v on-when-car-is-on valve, and I believe the L28's is the same. No need to hook it to MS, just have it powered when the IGN is on.
I used just that cold air valve and never had any issues with MSII on my Z31. And it had power steering and A/C. Although now that I think about it it has a separate PS up-idle valve.