The idea with a Bt top end on an St bottom end is the 1.8mm gasket gives Cr of 9:1 ( good response but will take modest boost ) if you swap the gasket for a decomp plate and two head gaskets your going to have a very low Cr. ( laggy but still with out the ability to handle big boost ).
I personally wouldn’t go to the expense of Arp stud and nut kits on a decomposing build. I would spend a few quid more on Rs pistons and forged rods at least

Mk1 Focus Rs injectors are are 440cc and could be had new for not a lot.

Blacktop fuel rail works fine. And are designed for the above injectors.

There are several firms making water rails and sumps ect.

My Rwd hybrid turbo. But I am already building a more capable engine.





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