You don't see them much on 12V's. The 62/68 I had was slow to light even with 5X12's injectors and a 4 in turbo back exhaust. I think it is that a 12V head does not flow as well as the others do. What mods are you have?
I am not sure what turbo you are talking about. Something custom or a off the shelf brand name? But here is my guess.
There have been many improvements made in turbos in just the last 2 years. I would look into a Borg Warner EFR sized to produce about 400-500 hp.
My reason, the newer design will spool better, ETT (extended tip tech.) were a vast improvement, so EFR incorporated ETT and Ceramic/Ti so they should be lighter, which means quicker spool and more air.
Or you could go with a small set of twins. But not knowing what turbo (Borg Warner, Holset, KKK, or what) it is difficult to make more than a general sugestion.
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