I think you would probably need to upgrade your injectors if you run the mani with the KWSC if you run the supercard. My experience with the supercard was lacking. not very linear fuel enrichment imo. but a good temporary solution.
The WR mani is awesome with the kit! however the welds did not hold up and started to crack after a couple of weeks. i think it was because in my case i also am running a bov which is heavier and adds more weight to the piping. plus the vibrations and engine torque. I tried different methods of patching it but no luck initially always temporary. finally a couple of weeks ago a removed it to change the plugs and install a header blanket. i used jb weld liquid weld and it has held up awesome. no problems. now i have to sand it down and repaint the mani.
Overall an awesome mod to work in conjunction with the kit. I have kept time with a wrx (not an sti) and an SI neither could pass me on the highway. although i still have no top end cause of the speed limiter. but that's ok a dont drive that fast anymore mostly highway driving no faster than 80 or so. But i get there much quicker.