The 93 Cobra ECU, and MAF are setup (collectively) for 24 lb injectors.
The caveat to that, is that the difference between those two injectors should fall within the ECU's ability to adapt (but doesn't always), so you can assume that you will probably run a little rich.
Exception: If you're running that MAF with your stock A9x and 19s, you should be just fine without a tune. The EEC and the 24s are the largest factor here. The MAF itself is designed within a tolerance that is very similar to OEM GT transfer function.
Bottom Line: Try it and see. Worse case is that you need a tune, have to drop your fuel pressure a little bit, or can obtain a 93C ECU for cheap.