Headers, maybe. My Mustang shifts at 11-1300rpm bust still gets 15-16mpg. Lacks o/d though.
A 6.2 diesel swap would be intriguing. I'd put my vote in for a 4-53t Detroit Diesel 2-stroke though
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'97 Honda Civic DX Coupe 5MT - dead 2/23
'00 Echo - dead 2/17
'14 Chrysler Town + Country - My DD, for now
'67 Mustang Convertible - gone 1/17