If you are going to add a turbo, you are much better off just buying a turbo 617 now, the easiest way to go (by far) from NA to turbo is to swap in the turbo engine.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth