If there was a possiblity of getting a tvs or a whipple supercharger instead of the stock one that they use in the kits, you can see better gains. The twinscrew style is more efficient than an eaton roots style setup which leads to better gains and a higher psi output. Along with it being a little cooler of an output as well due to the efficiency. With the roots style, all the air that enters the supercharger doesnt always exit and gets recycled and in the process heats up. From your sig, helios, from my experiance with the eaton roots blowers on my last car, the 14psi you are seeing is basically it for them. Sure, a smaller pulley can see more, but you get very minimal gains from the heat build up. A twins screw can go well into the 20s.
And im not 100% on this but i believe that an air to water intercooler is better than an air to air. The same reason you dont see aircooled engines anymore is that air is horrible for heat transfer. Water just absorbs and disperses heat much better. The only downside to the air to water is that there are more parts that you need to make it work and also doesnt have a big intercooler in the front of the car to look sweet but just a normal looking radiator. So if the electric pump were to fail, you basically lose a huge chunk of your cooling ability were the air to air is just always on. I dont see 375whp out of the question for a single supercharger setup. Its just whether you have the money to get there since that would be strictly custom and not available off the shelf from a store.
