I also agree with Val (*GASP*) If your happy with making 400whp, then why sink money into a single turbo. no need for it IMO.

I just think IMHO that you are ASSUMING alot right now based on LITTLE INFO. I would personally ditch all the electronics, use an SAFC an a boost contoller an get it tuned. See what power it makes THEN. respond back here with the a/f ratio graph.

Slapping a single turbo on an already low compression cylinder is another mistake. right now the only mistake you have is a car with upgrades an no tuning done what so ever. big no no. bite the bullet, buy an SAFC an tune it. Youll need AT LEAST an SAFC with the single turbo anyways so its not like its wasted money. If you tune it, the comp numbers stay low an you make crappy power, then look towards a rebuild.