you can use the cold start valve. Most people buy thr mf2 system from erl. The 5th injecter system can be used for water injedction aswell and can be programmed to work at different rev ranges. Also you can use a larger injecter if you need to. A friend of mine uses the mf2 unit and mad 267 bhp still using the old mfi system with a 2.1 zvh.