I had this same issue you are having. The 550cc are great for what you are looking for. I have been running a stock ls with 10-11psi of boost on a basemap untill I get to a tuner.

Just get your ecu chipped and get a basemap. install the 550cc and get a walbro 255 fuel pump and once you do that you get a tune and you will be well in or around 250+hp to the wheels. Goodluck